My name is Kevin, I don't have a blazer, but I have a 1987 chevy silverado, 350 fuel injection, it also has a high performance chip in it. I have come across a problem where the truck will randomly cut off, as if I turn the key. It doesn't matter hot or cold, when I go to crank it back up, the engine cranks and will eventually fire, then cut right back off. Once the engine finally starts it runs as if it is getting too much fuel, and black smoke comes out the tailpipes. If hold the throttle down it clears up and will run fine until the next time it cuts off. The truck also has dual tanks. I have replaced: Distributor, plugs, plug wires, coil, computer, fuel filter, fuel pump relay, coolant sensor, both oil sending units, idle air control valve, map sensor, throttle position sensor, egr valve, egr solenoid, the throttle body has been rebuilt, o2 sensor,switching valve on the dash, put on new grounds and replaced other grounds. This has become very frustrating, I have taken it to multiple repair shops and they tell me they can't fix it or don't even want to look at it. I need help here!! Thanks!

 

I had a similar problem. It was the ignition control module under the cap. Did you replace it when you changed your distributor or re-use the old one?

did you ever find out what is was?