Originally Posted by SouthArk370Z

Did a quick search of the Net and came up with the following possible causes of a P0300 before I got tired of looking:
Faulty spark plug(s)
Faulty ignition coil(s)
Clogged or faulty fuel injector(s)
Intake air leak
Fuel injectors harness is open or shorted
Fuel Injectors circuit poor electrical connection
Ignition coils harness is open or shorted
Ignition coils circuit poor electrical connection
Insufficient cylinders compression
Incorrect fuel pressure
Vacuum leak
EGR system malfunction
Low compression
Camshaft or Crankshaft sensor(s)
Faulty ECM