do mustangs come with marbles in the engines???

[mustanger82]

what it sounds like your experiencing is detonation( which can cause big problems, broken pison skirts, melted pistons etc...), possibly retard your timing. Or run some combustion chamber cleaner to clean up your motor, sometimes the built up carbon in your combustion chanbers and retain heat and ignight fuel before actual spark plug igniton. hope it helps....