I would check timeing First most likely the problem. Other then that Clogged injector. I suggest takeing them out of the manifold and cleaning them up with some brake cleaner. Clean each injector screen. This is a much better then just injector cleaner in the tank. You could also be haveing a miss fire. Bad coil, Bad Ignitor, Bad Wires or Bad cap and rotor. You might want to take off you Dizzy and make sure it spins freely if it is hard to turn that is you problem. As the bearing in them are know to go. Their should be some resitance but if you got to try hard to turn it, it is bad. If it continues after all those things are in working order I would say you got a valve problem one is sticking or bent. But that would be the worst and is most likely not your problem. What computer are you running any check engine lights? The si computer will runn it a little ruff but it should not spudder