power loss

[txhunter30]

I recently did a de-carb on my motor and took it out to run it at wot. After about 5 minutes at wot it started to lose power on me and eventually died. Would not restart. Compression before the decarb was 82 top, 72 bottom. After decarb 96 top, 92 bottom. After the lake run I checked it again and it was 96 top, 74 bottom. The engine will start in the driveway but dies as soon as I put the muffs on. This is leading me to believe water is somehow getting into the bottom cylinder and causing a loss of power??? Any validity to that theory??? What gaskets should I check and would that explain the drop in compression on the bottom cylinder? What else could cause the motor to lose power and die under load. It is a 1974 Johnson 50 hp. Has undergone de-carb, new plugs, very good spark, carb rebuild, timing check, new fuel pump and hoses. Any help will be greatly appreciated.