For awhile now I've had an occasional "buck" when driving at steady speed. The engine just hesitates and then goes right back to running just fine so I haven't been able to pin down what is going on.

Don't know if it's related or not, but this morning after driving for about 20 minutes, suddenly the engine is bucking like crazy as I try to accelerate from a stop. I pull over and the engine dies, but starts right up again. When I try to go, it dies again. Finally it works on the 3rd try, but as I'm driving I notice that the tac needle is jumping all over the place even when the engine isn't bucking and it continues to buck intermittently.

Normally I would suspect points, but I'm running a Pertronics Ignitor that has been working fine since I put it in back in May. I've run these units in 5 different Type 1 or 4 air cooled engines and never had a problem. Has mine suddenly gone bad or am I looking for something else? All the connections to the coil & injector triggers seem nice and tight.

maybe a major intermitent ground issue?

Fuel injected? check the cht connection.

I have to agree with Seanery, it has to be a grounding issue. That would make the tach jump and the engine stutter. Check your wiring for cracks.

I discovered that the coil had turned in its mounting bracket and one of the connecting wires was apparently coming into contact with the engine tin. I'm running a blue coil and it is smaller than the stock bracket so I had used something to fill the space and apparently it became compacted enough to allow the coil to turn.

The bucking is gone and the tach doesn't swing anymore, but now I've got a new problem that 9 times out of 10 when I try to start the car it will just crank & crank on the first try, but not fire. I turn the key off and try it again and the engine starts right up. Strange...