I've seen Sea Foam, but never tried it. I actually pulled one head and removed the two valves in that one cylinder and cleaned them up on the wire wheel. They were really encrusted. I then ran a product we sell at work called Power Tune that you spray down the carb of a running engine until the can is empty and the engine dies. Let it sit for a while (mine sat for 3 days, but they say 15 minutes works) and when you restart the engine crud like you won't believe blows out the pipes. My compression in that cylinder went from zero to 195 or so, through the wire brushing and Power Tune.

After that I put a heavy dose of Mercury Quick Kleen in the tank and drove it. When I checked the plugs they are burning light tan now. I also cut the fuel pressure down to 3.5 lbs and put a hotter thermostat in. The car now runs at 170 down the road instead of 150.

I never knew carbon buildup could kill an engines compression like that, which is why I agreed with you that he should check his compression. Bet he has a similar problem.

Don