Ricky 91 vette

U will need to make sure that your TPS voltage at idle is reading 0.54 v, and your IAC has about 50 counts with e brake on and shifter on drive and Ac off, if Manuel I think it should read 30 counts on neutral , you will need to set the TPS on 0.54 and check the IAC counts, and adjust the idle screw if needed and then go back to the TPS and re adjust it according to that . I hope this will help

21boy

Have sane issues as OP after similar tune up. What was result? Ever figure out issue?