Intermittent Shaking

[Grandpa]

I just bought a 1989 Johnson 28 SPL. It seems to start and idle fine, but most of the time I can't take it above about 1/4 to 1/3 throttle before it starts shaking side to side. Sometimes though it will go to WOT and seems to run fine, but all of the sudden it completely looses power and starts shaking again. I recently replaced the fuel pump, and removed, disassembled and cleaned the carb. Could this be a fouled plug or sticking reed?

[Rebel Sympathy]

I doubt if it is a reed valve. If a reed valve were damaged it would not sometimes run okay.

It sounds more like an ignition problem. Probably a coil or the power pack. Both can come and go when going bad.