Check your compression first. I would guess you have a piston problem. On second thought, if you have a bad piston you should have a lot of blow-by in the crankcase. Pull the oil cap off and watch for pulsing pressure while running.
If it is a pistol problem there could be real trouble. We don't want any excuses for gun control.:laugherJohn,
Thanks for the response... I'll do as you recommend and see what's going on. If it's a pistol problem, I would imagine that it will require pulling the engine. Probably shouldn't get ahead of myself here...