I have a 98 Limited 5VZ-FE 235k miles. Recently the truck has started vibrating/shaking when I give it gas/accelerate. It seems to run fine while idling but trying to accelerate/increase speed/climb hills causes shaking and it feels like either there is a loss of power or as if something is trying to hold the truck back.

This is a fairly sudden problem. I did wear out the front brakes very severely (literally wore the rotors down to the point the rotor face separated from the hub) so I wondered if maybe I messed up the rear brakes to the point something is locked up, but the wheels all turn fine. Also, I haven't one any off-roading or hard driving in the past 20k miles or so, just daily driving on pavement.

Thanks for suggestions.

Or your front calipers are seized up.

What does your brake feel like?

I just redid the fronts- new calipers and rotors, front brakes feel normal, just fine.

When this occurs does the CEL light flash/blink? Any CEL codes set or pending? Flashing CEL is indicating to back off the throttle, too much unburnt fuel is making it to the cat. Let us know....

So the CEL has been on for awhile and getting the codes:

P0125 O2 Sensor heater Circuit
P0135 closed loop fuel control insuff temp
PO 171 too lean bank 1
PO 177 Fuel comp sens circuit

Would all this cause the vibration that seems to be coming from the right front though? Gas mileage is very good right now, wouldn't it get worse with all those probs?

When I redid the brakes recently I did notice the CV boot was ripped on the vibrating side and there seems to be a groove worn into the shaft (I do have a lift, SS 1.2) The CV dies not click or pop when turning though.

Thanks again

Does it feel like an engine misfire? Or a driveline vibration? I'm wondering if perhaps you have a failing driveshaft U-joint? Does the vibration occur when cruising at a steady speed, like on the freeway, or only when accelerating?

The engine seems to run pretty normal, no skipping. The RPMs seem a little low, but only by maybe 500- sorta feels like if it was a standard transmission and you were trying to climb a hill in too high of a gear. Even when you make it downshift though it still vibrates and feels like something is pulling it down. Mostly its wicked vibration that seems to be coming from the right front and that feeling like something is holding the rig back.

I’d definitely look into fixing your CEL’s first.. I’d also go under your truck and do a quick visual on your driveshaft/u joints. But if it drives normalish when your going downhill/flat then it would seem like it’s the engine/transmission.. Just from reading the CEL description your probably not getting enough fuel to the cylinders and that’s why your getting such good mpg.

Is the shaking/vibrating only while accelerating? If you get up to speed and then shift to neutral and coast does the vibration go away?

Yikes, that's enough to make the engine stop running altogether...

Start with the P0135 O2 Sensor Heater circuit. That's the front O2 sensor and costs only about $50 on Amazon. Honestly, that might clear all of them up. Install the sensor (simple, 2 bolts and one wire connector) and then pull either the EFI fuse or the negative battery terminal for about a minute and put it back in. See if the codes come back, if any.

Can I ask though who pulled the codes or what code reader you used? A P0177 isn't a possible code on a 3.4L 5VZ-FE, we don't have a fuel composition sensor.