My 1992 Pontiac Grand Prix will not idle

PULL E.C.M FUSE OT DISCONNECT BATTERY FOR 20 SEC IF NO CHECK ENGINE LIGHT ON AFTER RESTART COMPUTER RESET

You need a new starter solenoid. It is essentially a heavy duty remote switch that is activated by your ignition key switch. The solenoids get stuck or don't conduct well after 6 to10 years.

disconnect the negative battery terminal first then disconnect the positive treminal so there are no accidents, raise the car safely go underneath & remove the starter cover should be 3 10mm bolts holding the cover on then remove the 2 through starter bolts 15mm then disconnect the + battery cvable from starter then disconnect the solenoid wire should be a 7 mm bolt. good luck

Check and service the starter motor, i had similar problems years ago.
hope this help.

I replaced a motor in a 97 and the engine was out for a few weeks and I never had a problem with an idle when I put it back together with a whole new engine. I would guess you forgot to plug something back in by the starter. Recheck everything you have done I think this is something simple.

provided you don't have a vacuum leak, (check all hoses for tightness and cracks with engine running) it's probably your idle air control valve or sensor.

replace the relay on drl lights it might be stuck close.

first remove the battery and take it to a auto parts place and have them check it. move on from there. if the battery is good the do a starter draw test. take a meter and hook it to your battery. now have someone try and start the car. if the voltage on the battery drops from 12.8 to below 9 volts then the starter is bad. if the voltage doesnt drop much at all then its prolly the solenoid both of which require starter replacement since most solenoids are on starters. if still nothing then check ignition switch. but before anything else ensure vehicle is in park. if it is in part use a meter to test neutral safety switch.

at rear bottom of engine, u must change it from the bottom. Make sure the battery is disconnected before u start work.

check your relay and underhood fuse pane to see if you pinced some wiring