Hello everyone, I'm new to boating this year. I purchased an old trihull and an unknown condition Johnson 55hp 2 cylinder. So far I've replaced the coils, stator, plugs (ngk 2129), fuel pump, rebuilt carbs and changed jets to the size listed in the parts manual. I tried to take this boat out last week and couldn't get it to idle without misfiring and stalling. Also top speed was around 7mph at 1200rpm. The week before I had it running around 24mph. Not sure where to go from here. I have tried synching the carbs and the throttle linkage to the cam. Cylinders are at 110psi and 115psi compression. Base timing was set to 4* btdc. Not sure what full advance is as the manual says don't rev the engine with no load. Any help is appreciated.