So while attempting to fix the random jumping idle i seem to have uncovered something worse. When i replaced the IAC with a good used one i have a high idle problem now. I mean like 3 or 4 k high idle problem. It goes down at some points but then goes right back up. It has been idleing so high lately that it has blown both of my headlights out. One went out 2 days ago and the other tonight. Any ideas where this super fast idle is coming from.

Sure the IAC was a good one,the other thing that comes to mind was the old one was stuck closed and the original erratic idle was due to air leaks around a worn throttle shaft,if that was the case then adding an IAC that works could cause an extra high idle.

Worn throttle shaft bushings will cause either a carburetted or fuel injected engine to have inconsistent idle characteristics.

This is due to the throttle plate never seating correctly the same twice and the lack of an effective seal around that plate will lead to high or inconsistant idle issues,quite often if this is the case when it idles high or low blipping the throttle a couple of times will alter how it idles as the plate will sit differently when this is done.

More obvious things such as throttle cables and accelerator pedals tend to be more obvious so I assume you have eliminated these.

Your headlights are being blown out?? High RPM's should not affect that at all, only if your VR was going out and allowing to many volts to the headlights. You got something else going on, ontop of the high idle. I would check my alt as well…

 

I would swap the other IAC in and see if you still have high idle, then it would rule out the IAC, but if your high idle goes away and the funky idle returns after swapping the IAC, you would at least have it narrowed down to the IAC being funky.