I have a 1990 lumina 3.1 motor. It will run fine for miles and then when you stop the motor will shut off. If you wait 5 minutes the engine will fire back up with no rough idle, sputtering or jerking. It doesnt happen all of the time. Its like someone turned the ignition key off. I have installed new wires and plugs.
No change. No check engine light on. Any suggestions ?

Welcome to AF, do you have spark and or fuel pressure when this happens, these are basic initial diagnostic steps.

I have had one with similar symptoms. It ended up being the torque converter lock out switch. I just pulled the plug fromthe front of the tranny and drove it another 30,000 miles with no problems.