Whats wrong with my 1990 Chevy Lumina Euro 3.1 Liter Multiport?
I’ve seen crank sensors act up like this. It’s too long since I worked on one of those to remember where they’re located. On a vehicle that age, it could also be wiring starting to cause problems. All it takes is a pinhole in the insulation to allow moisture in, and that’s when problems start. Also inspect the harness anywhere it can rub on part of the engine. If a signal wire gets shorted to ground, that can stop things pretty quickly. I know you said you changed the coil packs already – but did you remove the module underneath at the time? If that module gets corroded where it mounts to the engine, it can also cause problems like this. I would try these things before throwing any more parts at it. The only other thing I can think of is this: does it have a MAF sensor? These were especially troublesome around that time, and GM actually had a fix available that required changing the PROM module in the ECM which was designed to ignore any signal from the MAF. If it has a MAF sensor, it
