2005 rxt wont go past 3000 rpm

[Seadooboss600]

I have a 2005 rxt that i just put in the water tonight for the first time this year. started it up in the drive way with a hose on it and it started right up. when i put it in the water, the engine died on me when i was backing it up off the boat launch and then it wouldnt go above 3000 rpm. putting new plugs in it and checking the compression soon. any other suggestions as to what may be the issue? thans

 

[68ragtop]

Good chance its a fouled plug. The engines will run "somewhat" smooth with a bad plug, but will feel like you have a learners key installed when you try to get up & go.