As described above. I am having the trouble with what I believe to be Idle air control valve/motor. I am wondering If I changed the wrong value in a table. 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. Is there a setting I might have changed I am unaware of or might have missed?

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 something to do with a MAT or IAT table?

 

Can an IAC motor even pass enough air to allow an engine to operate that high? 3000 rpm?

Are you sure there isn't some large vacuum leak someplace? Maybe somehow it's an intermittent vacuum leak?

Try this: disconnect your IAC completely, then set your idle speed with the throttle blades. Drive around and see what happens. If the problem goes away, then you know it's the IAC motor. If it doesn't then the problem is elsewhere (vacuum leak, stuck throttle blades, etc.)

 

Will try. I believe that it is IAC because when it only goes to below 3000 rpm after I have taken my foot off of the pedal. And if I tap the pedal quickly, it goes back down to idle speed 800 rpm

 

Sounds like a vacuum leak to me.

 

You just need to scan and/or log this, and check your idle air counts before during and after. That will tell the tale. Without capturing the event in a log we're all just guessing.

 

Went and did plenty of tests on it. found out it is a throttle body that needs a new throttle return spring. It would stick open a small amount. The reason it would gain RPM when out of gear is because there was no load on the engine, therefore would rev/idle higher. I disconnected the IAC, then logged it on the laptop. IAT needs changed, but that was not the real cause. The spring is barely strong enough to slowly bring it down to real idle-thus making me think it was a slow/bad IAC. Thanks to all.