first off my 89 rs 2.8L had a surging idle, it was very erratic. So I changed out the throttle position sensor, cleaned the throttle body, and changed out the gaskets. Now my idle is just over 2000 RPM. This is after adjusting the idle as far down as it can go. I have also replaced the EGR valve, EGR vacuum solenoid, mass air flow sensor,l and the fuel tank filler neck. but I am out of ideas.Any suggestions?

 

Since you messed with the throttle adjustment once you figure out your issue your gonna have to set it back otherwise it will stall at every stop sign and traffic light...ask me how I know . High idle could very well be a vacuum leak. If your vacuum lines look old and dry rotted it's time to replace em. Also check your IAC valve, a faulty one could cause high idle. Setting the TPS to .54 volts helps bring idle down a bit too. I had idle issues for the longest time while working towards getting my car road worthy trust me you will eventually find the problem.

 

Thank you for your insight, tomorrow I am going to take out the IAC and clean it to see if that helps