2002 Mustang GT Deluxe manual Idle issues.
Hello, I read through the sticky post on idle problems and did not find an answer to my problem, which has been evolving.
It started with my idle hanging around 1000-1200 RPM then returning to normal, I removed and cleaned the IAC, which caused the idle to start bouncing between 500-900 RPM. I then replaced the IAC which solved the idle hunting but it started pulling codes for not having any more adjustment. I hunted down vacuum leaks and found a big one going to the PCV valve and fixed it, I also took the time to clean the PCV valve at the time. So it no longer codes.
What it is doing now is whenever I take the revs above 2000 RPM the idle will hang around 2100 RPM for around 10 seconds and then drop and die unless I blip the throttle and keep it running. If it does die, it will start right back up and run just fine. I thought I got a bad IAC so I went and got another one, but it did the same thing. If I put the old IAC back in it will buzz/rattle at idle now, but there is no hanging problem. With the new IAC in the car if I drive it and keep the revs below 2000 RPM you would never know there was a problem. If you compare the new and old IAC's they look identical on the outside but on the inside, manifold side, they are different. The new one has a shaft/spring assembly where my old one does not. I asked the guy at NAPA about it but he swears that I have the right part. Oh, my car is all stock except what looks like a K&N air filter (prior to me).
Any help/suggestions would be awesome... Thanks!