P0300 CODE

1996 Chevrolet Silverado • V8 2WD Automatic • 157,000 miles

I have a 1996 chevy truck with the 305. My check engine light came on and when checked they said it was a P0307. I changed the plugs, wires, cap, rotor and spider injection system. The light went off briefly but has returned as a P0300. It will be on for a few days, then go off for a couple, then come back on. It does have a gas smell in the oil, but no signs of any leakage. I have also noticed a vibration and rattling noise coming from either the torque converter or the flywheel. The transmission was rebuilt 2 years ago. About 15000 miles has been put on it since. Sometimes it will also leak transmission fluid. Gas mileage seems to have dropped substantialy. Could these problems be related and whats the easiest, cheapest solutions? I have tried to find the exact problems, but the P0300 code can be a tricky one.
November 29, 2010.

P0300 Random Misfires can be tricky but normally caused by vacuum leak and contaminated fuel-

Nov 29, 2010.
Your answer to my question didnt really tell me much. What do I need to check first?

You can start with vacuum leaks. Coil, fuel pressure and EGR valve

You had a specific cylinder misfire on 7 now its moving around-you need to start checking what I've suggested this is not a simple fix over the net it needs extensive troubleshooting otherwise request for refund

Nov 29, 2010.