Hi All: Thanks for all the helpful replies. I went with the recommendation to pull the plug wires individually while the engine was running. As I did so, I observed the engine RPM on my shop tach. Every plug that was pulled showed an RPM drop, then an increase when the plug wire was re-installed. So I was wrong about having a dead cylinder. All the cylinders are firing, which I've confirmed. Something else, probably more serious, is going on as the engine is running just like it has a dead cylinder. I'm puzzled by this and cannot find the cause. The choke plate is fully opened when warmed up. No vacuum leaks. No exhaust leaks that I can find. New plugs. Rebuilt (stock) carb. Maybe I've got something bigger going on. Had the head re-done (grind valves, new valve seats and guides, etc.) about 15K ago. Think I might need some professional help on this one. This motor should drive and idle smoothly and it doesn't. Very frustrating, but I'll keep searching.
