Need help please! Acceleration problem

[MartinaMCL]

My 2002 Seadoo Challenger 2000 with 240hp is accelerating and then decelerating unexpectedly. Also when it slowed down, I throttled up but there was no speed response. It continued at the same slow speed. This happened last summer and a mechanic replace plugs but now I have the same problem. Please advise. Thank you!

 

[bledt]

Oohh, the Mercruiser. I hate to tell you but not many people here know alot about that engine. Best of luck to you!