when warmed up, and stopped i can hear what sounds liek a snapping noise coming from teh right rear of the engine. i have a 94 360. its worse when in drive, brake on at a light or so. it stutters the engine, never stalls, it is just rough. sometimes it will snap like 10 times in a row, others just once or twice. it is getting worse. it is on the drivers side, toward the rear. its not spark wires. i have a new cap and rotor and plugs.