Walt, this is dejavu all over again. I think you tried swapping the plug leads to the other cylinder. What happened to temperature then? If the cold cylinder didn't move with the plug lead, then it's likely something mechanical. Maybe a ring is sticking on one cylinder when hot? Perhaps one cylinder doesn't have adequate piston clearance? I'd pull the cylinders and have a look inside. It's hard to understand how CH would "fix" the bad ignition and it would still be a problem....low probability.