99 limited 170k 4x4 BONE STOCK my truck ran beautifully like silky smooth on the road until one day I was coming down from Jasper on a steep decline I braked hard twice almost coming to a complete stop but not quite. as soon I got back on the throttle after that I had a vibration through the whole truck like something was holding it back I can feel it in my face ears in the gas pedal under my ass in the steering wheel and it is just not a joy to drive (funny cause right before this happened I was parked somewhere and i had a moment where I just was thinking this truck is just the flippin best! HAHA) i have taken her to many certified mechanics I get the same thing nothing is wrong and that everything has been checked out suspension rear brakes body mounts motor mounts but I know there's something wrong. THE KICKER WITH ALL THIS IS THAT THE VIBRATION IS HORRIBLE ON THE HIGHWAY BUT I FEEL IT IN PARK AND NEUTRAL AND EVEN MORE WHEN I REV IT?! AND IT ALL HAPPENED AFTER THIS ONE INCIDENT! I have a heavy foot and I now have trouble keeping speed above 120km/h. I have replaced the 2 engine mounts but not the tranny mount. I noticed a hole in my muffler so replaced it with a flowmaster but did not weld the stock muffler dampner back on... or could it be the harmonic balancer was shot? Is it possible I broke something inside the motor? my tailpipe also shakes a lot. could something have broken off inside the exhaust system? I am leaning toward motor and exhaust because like I mentioned I feel it in my face and ass in park and neutral. any ideas or suggestions as to what else I should look for will be greatly appreciated and I thank all you 4runner lovers in advance!

Is there any time where it does not do it?

They're a strange one

Are you able to share a video (with audio)?

thanks for replying!

I guess no there is not a time when it doesn't do it. maybe before I turn it on. so strange to me. I bought a crappy 98 2.7 4x4 and it does the same thing but it has double the mileage and I expect that from it (I actually think the 4 banger is smoother at high speeds... maybe). its like I just crossed the new truck feel to old truck feel threshold haha

I cannot supply a video of it running at the moment because I took a lot of the top end engine stuff out for no good reason other than to maybe get a visual on something out of whack. i could see the motor shake ever so slightly and it seemed like it was coming from the top of the throttle body. it has been a year since I have had this problem and I have done a lot of stuff suggested on the forum like clean maf tb iac seafoam changed the rear joint then the whole driveshaft (used, then I thought the used one was bad so I took half from the old one with the new u joint and put together with the big part from junkyard shaft thinking I made one perfect driveshaft) that I would never have done had I not encountered this issue so I don't know if I now have multiple issues. my broken muffler was definitely a cause of some of the vibration my j shifter would rattle very audibly at lights after I got the flowmaster it still shakes never made a noise again and I still feel the shake in my face.

maybe she just doesn't like me

Did you damage the torque converter or flex plate?

When you did the hard braking did the engine drag down in RPM as the vehicle slowed?

Sounds to me like the torque converter didn’t release and got damaged.

In park you’d be spinning the engine, flex plate, torque converter, and tranny pump/input.

So it should be a large spinning mass that causes the vibration.

On the front of the engine you have the harmonic balancer, fan, alternator, Power steering pump, and AC pump. You could remove the belts and test.
Visually inspect the harmonic balancer.

My vote is flex plate and or torque converter.

I am still learning how vehicles work and I appreciate your suggestions. if you don't understand the mechanics its impossible to pinpoint. I hope its not a torque converter but at least I have some new ideas thank you!

its hard to remember what the tach was doing cause there was a deaf deer on the road. how to I inspect a torque converter? I noticed recently a large leak from the front of my front driveshaft at transmission. related? I can't remember if I was in 4hi at the time. I think I was.

I’m keying off you saying the vibration exists with the tranny in Park and Neutral.

In those scenarios very little of the tranny internals should be spinning. The Transfer case shouldn’t be spinning, not the drive lines, axles, ect...

Also keying on your comments that you’ve taken it to “many certified mechanics”.
A mechanic would generally find external things fairly easily like mounts, harmonic balancer, exhaust, misfiring cylinder, ect....

But...mechanics aren’t all tranny guys, and torque converter, flex plate, ect.... are internal to the bell housing, more difficult to inspect and diagnose, and much more work and expensive to just swap out to see.

Fairly easy to pull the belts to test those items. Fairly easy to test the balancer (crank pulley) for run out, visual for cracks or missing chunks.

Miss fires should give an engine code. Can’t imagine you’ve ran a year on 4 or 5 cylinders without the computer noticing. Mechanic should have found that easily as well.

+1 on TC...I know a guy whose bolts mating the torque converter to the flex plate had backed out. Since it happened suddenly perhaps one or more on yours has let go.

Sell it or trade it in for something else you want to drive. If it is that much of an issue for you it definitely would not be worth the headache on a 20+ year old vehicle for me.

what you guys are saying makes sense. the vibrations while not in gear are extremely light but once I'm going fast they feel heavy. I feel it the least when I'm cruising at city speeds but they are always there. I know its not a misfire I've already had 2 where truck threw codes was undriveable and it was wires and a coil to fix (separate occasions). a broken or out of place flex plate hopefully but I seen around that a broken flex plate will cause a loud ticking noise. I never noticed a noise until about a month ago when I'm in gear the transmission makes a hissing noise and there is a light ticking noise coming from bell housing area. not even close to as loud as some of the videos I've seen but it gets worse when warmed up. also my overdrive works the same as always so is my tc okay or still could be damaged? I work at an auto parts store and have gotten to know some tranny guys so I will take it to one I guess. I don't like paying for labour anymore can I inspect this myself? I am in no rush I have parked the truck for now cause I moved provinces.

this what my mother said. she's always right. I am at that point but not just yet I guess. I've had newer runners this was always my dream vehicle like on the brochures when I was a kid and stuff I spent a lot making it as close to new as I could (like an idiot) so I would like to try to figure it out if possible.

moms are not always right (nor are dads)3rd gens are super great. Spending money on it might not be stupid.
hope you get it figured out. let us know what you find out.
you said it was great until you were coming down a hill and had to brake hard several times then the vibration started...to me sounds like a brake issue
but sitting still and there is still a vibration says something else is wrong and not in the brakes or rolling parts. In that case I think there is more to it....more than just hitting brakes coming down hill..
come clean with yo mama...what else where you doing

A bad torque convert like you describe kind of unusual I would do a bit more checking before pulling the trans and replacing the converter. Maybe do a compression test and look at the plugs and wires. If they are past due change them first.

haha lots of dirty stuff which makes it even worse this happened on pavement! have jumped the vehicle a couple times but no issues and when braking I just remember it lurched forward like crazy. the morning of my travels I took it to Toyota to turn drums and change shoes and when I picked it up they told me I just needed an adjustment so when this happened called them right away and had them credit me for the service lol by the time I stopped for fuel realized it wasn't just a brake issue. still pulled the drums and did the driveshaft stuff and have learned a lot just trying to save money but am not any closer to finding the issue with my truck unfortunately. I also think there is much more to it. Will investigate more and post back!