I'm another idiot that turned the TB set screw, trying to raise my idle. Feedback from this site got me started on the correct path, unscrewing what I had done...almost. I went back to basics, turned the set screw to where I thought the butterfly's were just about "slightly open ?", set my TPS @ 0.60..AND WA..LA smooth idle again, a little high (860-70rpm) in park, but smooth. All of a sudden, I get a trouble light, and the guy at Advance says it's the IAC at it's limits (or words to that effect). Here's my question, before I go out and spend money on a new IAC..........Could it be that I just opened up the butterfly's too much, or maybe not enough, causing my IAC to be at it's limits? Again, TPS is set @0.60 at stop, and vac gage reads a steady 21. Engine runs fine with the exception being the idle is just high 870rpm in park. Thanks, Jimm

 

This depends on your transmission. Target idle RPM for an auto is 550rpm, 650 in neutral. 6-speed cars have a target RPM of 800. If you have a 6-speed car, I'd say there's nothing to worry about. The stock tachs are notoriously inaccurate.

If you are an auto, you need to check your IAC counts.

 

If you have a particular trouble code, post the number.