04 gc hwy driving prob.

[ericpaul80]

First off, hello everyone, new to the forum.

Want to pick your brain.

I have an 04 gc overland 4.7L V8 w/ 43000 mi. It works great in the city, but at interstate speed its RPM's jump around. At 75 mph it runs around 2150 rpm, but then it will bump up to 24-2500 for a second (almost like its trying to upshift) and then go back to 2150. It is worse with the cruise on, but does it regardless of cruise or me on the accelerator. Last night the Check Engine Light came on and i got a code of P0121. I think it refers to the TPS. I was wondering if it could be this or if it could be a clogged fuel filter (i.e. the engine senses it is not getting enough fuel and increases the power to get more fuel), or if it is something in the transmission (? pressure sensor in the auto shifter), OR if it is having a hard time getting into and staying in overdrive.

If you all think it is the TPS, could you let me know where this is located and how hard it is to fix. I know my way around the car, just not well enough to know what part is what.

Thanks for all the help in advance and hi again.

[ericpaul80]

i forgot to add that after getting off the interstate and parking the engine will idle wierd. It usually idles at 600 rpm, but it will bounce between 600 and 1100. It only does this after interstate driving.

[xj31]

P0121 is tps does not agree with map.By your symptoms,it does sound like a bad tps.