So i've been having an idle issue lately with my 87GT. First it was idling erratically...then i replaced the IAC and removed the TB to give it a really good cleaning..i re-installed everything and decided to take it for a test drive round the neighborhood....now when i first let off the clutch and give it gas, it spits and sputters and then takes off...when i left off the gas it idles really high...i'll hold the clutch in and smash on the gas and that seems to lower the idle some....one time when i had the clutch pushed and stomped on the gas to rev the engine, my check engine light came on...when i checked the codes i got a code 24 which is indicates a problem with the speed sensor..anyone have any suggestions or tricks where to start trying to diagnose the problem? like checking for vacuum leaks and things like that? thanks

Did you set the IAC before you installed it? The ECM automatically adjusts the IAC, but only if it is installed correctly. See below ↓
If not that then I would look for a vacuum hose that came loose.

quote Originally posted by Gravitic Anomaly: Did you set the IAC before you installed it? The ECM automatically adjusts the IAC, but only if it is installed correctly. See below ↓ If not that then I would look for a vacuum hose that came loose.

hhhmmm..i did not but i will

i did a vacuum leak test last night by removing the iac and plugging the hole...the car shut down immediately...it's my understanding that this means no vacuum leaks....aside from adjusting the iac as stated above which i will be doing tonight, anyone have any other suggestions on what else i should check while i'm at it? thanks

When you cleaned the throttle body did you accidently move the throttle position sensor or some get solvent into it? A flakey TPS might have been your problem all along.

- Tim