As described above. I am having the trouble with what I believe to be Idle air control valve/motor. My problem is this: When driving (manual tranny) and I shift out of gear to put it in another gear, the engine revs to just shy of 3,000 RPM. If I leave it out of gear, it will slowly fall down to 1200 rpm. Sometimes it will stay at 2000 and sometimes 1500. It will also act as cruise control and stay at the same rpm I have the accelerator pedal at.

I replaced the ignition control module and IAC last week. The new control module did not help. The IAC motor made the problem disappear for about 3-4 days, then back as usuall. I am positive the throttle blades are not stuck open. could it be a bad MAT or IAT sensor?

 

I had a similar problem. Mine was actually more apparent in cold weather. My throttle cable was sticking somewhere.

 

Have you checked/set the throttle position sensor?

 

Yes, I have. I even went as far as to back probe the tps connection at the ecm to verify the correct voltage. I will check again to be sure though.