Quote Originally Posted by reva View Post
no i did not replace the crankshaft position sensor.. do u think that could be the problem?? i guess i could try the compression test when i get home from work.. whats a leak-down test?? also my dad seems to think the computer might need reset,, how would i go about doing that??
I think using the old sensor is fine. Whatever it is, it needs to have the relearn procedure done if you keep getting the P0300 code. I reset mine a bunch of times while trying to fix it and it always came back.

This explains leak down testing: Leak-down tester - Wikipedia, the free encyclopedia I would probably only do a leak down test if the compression test doesn't show anything wrong. But, if things are bad enough for the engine to run that badly, you'll probably see problems with the compression test.