Two days in a row now I've had an odd loss of power. I have an 04 SR5 V8 with 63k miles. After driving for 25 mins on my commute home, I hit a stop and go section of traffic which is on a gentle incline. After sitting stopped for a minute or so waiting for traffic lights, I get very sluggish throttle response and very late transmission shifts. I pull over, turn the truck off and restart after about 30 seconds and all is good again. Nothing is lighting up on the dash and these two times are the only occurrences of this.

I don't think it's the brakes/calipers hanging up because there are other areas on my commute that I have to sit and wait for lights and it doesn't occur.

EDIT: Also, yesterday the AC was on, today it wasn't.

Any ideas?

Also had to stop short a couple of times this morning in traffic-stupid NJ drivers. When I hit the gas, I heard and felt a pretty large bang as the trans dropped back into first gear. I also recall during the power loss yesterday that I heard a noise almost like the serpentine belt was slipping/squealing a little bit.

Thinking this may be a trans fluid issue, I called the local dealer for a quote on a non-pressurized trans flush and they wanted $250. Seems steep but I haven't had work done at a dealer in a long time so that may be the going rate for that type of work around here. I also called a mechanic that I've used in the past for work I am too lazy/don't have the tools to do and he said something about a pressure control solenoid in the trans that can cause this type of issue. Has anyone had to have this part replaced before and what did it cost?

Had the trans flushed and the problem seemed to go away. Until today-after I changed the plugs and cleaned the MAF and throttle body I took it for a test drive and had the power loss scenario happen again. Pulled over, turned the truck off and on and all was back to normal. I'm stumped.

I had this problem before too, and in my case it was a low trans fluid issue. Started out as feeling like the driveshaft clunk everyone describes but eventually (a few months) manifested itself as a complete loss of power despite increasing revs of the engine (probably due to being in 2 gears at once!). Seemed like it was stuck in 1st-2nd, then managed to get to 3rd and was OK to keep moving. Shutting down and restarting worked a few times but I didn't want to get stuck so had it fixed.

After a proper tranny fluid change its been fine since.

I would venture a guess that they didn't set the fluid level right after the fill. I'd go back and have them check the level in accordance with the service manual.

Mike

OP, did you ever solve this? I'm in the same situation. No CEL and the revs don't increase.

I had a similar issue. I came out of a restaurant and my truck was dead out. Wouldn't start, wouldn't turn over, etc.

I get a jump from AAA and on the drive home I was having intermittent power issues where the whole truck felt like it turned off.

After I got a new battery the problems I had on the way home never happened again. So check your battery and make sure it's in good condition. Low voltage issues can cause havoc on on heavily electrified trucks.