Pontiac Repair: random misfire, camshaft position sensor, crankshaft position sensor

Question
1999 montana getting p0300 code replaced spark plugs coils and wires still having same code should i replace ignition control module or could it be the PCM ? NOT getting a camshaft position sensor or crankshaft position sensor code still having major misfire. I was told it could be an upper and lower intake manifold gasket causing a vacuum leak.Forgot to let you know that it has a 3800 eng.

Answer
Hi Dennis:

If you live in the states they didn't put a 3800 in a 99 Montana. It's a 3400 engine. If it has new plugs and wires. The next thing I would tink is a dirty fuel injector. Are all the coils good? usually on these enegeisn the coils have issues where the wires would either burn or rust/corrode on the coils. If that is the case replace any affected coil. A vacuum leak usually will not cause a misfire unless it's a bad enouigh leak and it would set a lean code to go along with a high idle.. So I would lean more towards a dirty injetor.. Try having them cleaned using a pressure cleaner on the injectors not adding cleaner to the tank. Good luck :)