fouling plug #1
 

had issues awhile back with backfires that turned out to be badly fouled plug, it was black carbon not sooty/oily but dry, anyways that cyl was firing intermittent at low rpm's but about 1000rpm or so it fired OK, turned idle up for now but still fouling that plug have changed wire and new plug but still fouling have not had time to change cap or do comp test on that cyl, anything else to look for, running pts dist with pertronix

Run it off petronix to see if it clears up