What we have is a 355 sbc. Went to the carshow this past saturday night and on the way home it started skipping. Replaced the plugs, swapped the wires, swapped the mallory distributor with another mallory distributor. Has a blaster coil which we swapped out, new resistor, drained the gas tank and put fresh fuel in it. Set the timing several times and still hasn't changed a thing. Any ideas??