Our 1993 Lumina also does that. I cleaned the IAC & it went out for along time. Today the wife said it was back on, then called me to say it was off again. I have never tried to pull codes. This Lumina belonged to a family member & has 237,000 miles without any major problems. So those that believe a Lumina is a piece of crap 237,000 miles speaks for itself. My wife commutes with it everyday 90 miles round trip. This light deal has been going on for 4 years I know of. But runs great light on or off. Still gets 20-25 MPG.