My 91 Grand Prix is a 3.4 with 5 speed Getrag trans. as the title says, it will start cold quickly settling at 1500 RPM for about 2 minutes, then drop to 1100 RPM and stay there. It has a cleaned throttle body, replacement of the Idle air control valve (4 times!) Verified throttle cables have slight slack. Backed off the minimum idle screw with no change. I confirmed the dash Tach reading with a hand held RPM tach/ dwell meter. I've checked the vacuum hoses that I can get to without removing the upper intake. They are either new or intact and secure. In all other respects, this car runs great. Good power, smooth idle and it gets to temperature (195 F) quickly. What's left?
