Good morning guys. I’ve seemed too developed a intermittent backfire through the exhaust I thought maybe it was choking itself out so I replaced the air cleaner and at the same time did the plugs rotor and cap. I checked for vacuum leaks and didn’t find any. I don’t regularly drive and decided to take it out yesterday. I was going about 60-70 mph and all of a sudden tack dropped to zero for a second and when it picked back up she fired through the exhaust (un burnt fuel before it died?) it did this 5-6 times and seemed to work itself out. The motor is the original 3f with about 250k on it. I was now thinking it may be a ground or alternator issue?? Maybe the distributor? Kind of at a loss and looking for direction. Has this happened to anyone else?