Okay.... so for the past couple of weeks my jeep (89 4.0L 5 Speed) has been running amazing with no problems... which is surprising.... anyway lately sometimes when i start the jeep hot or cold, it will rev up to 3,000 rpm and stay there... However its intermittent but its getting worse. Over the past few days its only done it maybe 8 times, and the rest of the time it has behaved, but tonight i drove to run some errands and it worked fine, but a few minutes ago i went out to go start it and i couldn't go anywhere because it would never go back down from 3,000 RPM. Also when its not stuck at 3,000 rpm the idle is really bipolar, and its at a different RPM every time the jeep goes back to idle at a stop light. I bought a brand new IAC 2 months ago. From what i have been reading it could be the TPS, CTS, or MAP sensor? I know better then to just throw parts at it, i figured it would be best to check here first and see what you guys think. I am leaning more towards the TPS but what is confusing me is it never dies, or sputters, it just has issues with the idle, and when it starts!

 

Buddy had the same problem, he replaced the TPS and hasn't had a problem sense

 

Ok thanks! Ill go and pick one up and hopefully that will fix the problem