2000 Grand Am stalls while driving

[Prankster]

Vehicle started stumbling when started, ran rough, 40 mph top speed, cat converter glowing orange. Error code: Random multiple misfire. Replaced coil housing, coils, and boots. Vehicle ran fine except it started shutting off while driving. Error codes: P0336 Mod $10 Crankshaft Position Sensor A Ckt Rng Perform, P0420 Cat converter efficiency. Replaced crankshaft position sensor.

Vehicle still shuts off randomly while driving. I can run full rpm shifts with no problem except a stutter ever 1/2 second or so. Just randomly shuts off (to idle) as the throttle is depressed and most often will resume before vehicle totally shuts off and has to be restarted. No error codes. Problem came on literally overnight.

New coils had primary reistance of .5 ohms each, secondary resistance was 9,100 and 9,300 ohms (books (Haynes) calls for "roughly" 4,000 to 8,000). Had Crankshaft position sensor variance learn procedure run by dealership. Still shuts off. Sensor reads 751 ohms and produces .002 AC volts (yes, that is correct) while cranking. Bad sensor? Tested voltage later and come up with 1.5 - .5 AC volts, not sure why. Spliced in new connector (8 wire plug) to Ignition Control Module , still same problem.

What am I missing? Please help.

[xeroinfinity]

welcome to AF.

Your cats glowing red, thats the problem!!!

The odd variance in voltahe you are getting from the CPS is most likly a bad wire in the circuit.

Also when was the last time the fuel filter was changed ??

[Prankster]

Fuel filter changed while trouble shooting. Cat no longer glows red after changing coil housing and coils.

Talked with tech from Wells, suggested try changing plugs (Autolight double plats with 9,000 miles on them). Guess what, engine quit shutting off. Problem now is that the engine will stumble randomly, but it is usually with part throttle when going uphill. Problem is getting worse the more miles I put on the plugs. I am stumped.