when ever i turn the a/c or the heat on my car idles kinda crappy, somtimes it will drop really low then bounce back up past regular idle rpm's. when i dont have anything on it idles perfect but with the a/c or heat it idles kinda funny and also when the a/c is on it will "surge" a little bit on the highway..any ideas of why it would do this..i was thinking the IAC or even throttle positioning sensor but dont know really

 

more than likely the IAC, do to age and the fact that the PCV valve hasn't been changed at the recommend 30k.

TPS's since @1994 up have been pretty much trouble-free, I could not tell you the last time I sold one because one went bad

 

diddnt mention this in the post but my car is a 99 gt..sold the 96 and havnt had the name changed if that makes any difference to you in the age part of it

 

nah, not really. I still say IAC and a new PCV valve are in order and Please stay from aftermarket stuff

 

two things you can try first remove the iac and soak it in carn cleaner over night. dry it off in the morning and restall it. Sometimes they stick. Second this one work weird. remover the hose that goes into the iac if it smooths out replace iac. I say this because i changed my plenum and had idle problems called accufab to figure out why. The tech said to try step one. However I told him about what I did in step two. Then I put the diagnosis on the car and it read iac. Don't know if the hose removal was just coincident or what. But I know I didn't find much help in forums so just trying to help