Hello Everyone,
I have a 2002 GMC Sonoma 4.3L VIN W. It has roughly 130,000 miles on it. Im getting DTC P0300 Random multiple cylinder misfire. I have done everything that I can think of. Here is a list of the things I have already replaced:
- Plugs & Plug Wires
- Distributor
- Distributor Cap
- Rotor Button
- Ignition Control Module
- Ignition Coil
- Crank Shaft Position Sensor
- Fuel Pressure Regulator
- I also took the truck to a GMC dealership and they put a GM Tech 2 on it and tested the injectors and they checked out fine.
- Also did a Fuel Pressure Test
- Checked for vaccum leaks

I am beyond stumped. The only thing I can think of that is left to replace could be the ECM/PCM. If anyone has seen or heard of this and has in info that they can pass along it would be very much appreciated. I forgot to mention the truck doesn't really misfire at idle only when driving. I hooked it up to a MAC OBD II scanner and monitored it. Every time its the same thing cylinders 1 & 4 are almost dead. Thanks so much for any help.