Engine shakes in gear, 1/2 power.

[Richard9090]

Took my boat out today, got it in the water; let it warm up (idled fine) put in gear and the motor starts to shake in forward and reverse. It seems the output of power is half of what it should be. I have a jet prop so from my knowledge it is not prop damage. Bad gas? Bad spark plug? Any suggestions on where to start to troubleshoot? Thank you

[robert graham]

What model/HP/year of motor?

[99yam40]

your complete model # is the 1st thing you should post when asking questions, so everyone knows what motor is being talked about

[Richard9090]

2000 Yamaha 115hp (115 TLRY)