Cliff notes. 25� Manitou tritoon would do 40mph with 200 SHO after breakin. After 2 1/2 years set docked at Twok it would only go 19 MPH at 4400 rpms. 4400 was max rpms.
Finally put it on the trailer and had it scraped/cleaned. Found the back 1/3 of the center toon was completely full of water. Syphoned it out, new in line fuel filter. Toons cleaned and about 700-900 pounds of water gone it ran29-30 mph and still only 4400 rpms. Has about 30 hours total on it. Wondering if the throttle linkage could have slipped? Any ideas. I know next to nothing about any kind of mechanics. Thank you in advance all.

Might need to put a computer on it to see if any faults show up

Thank you I may have to take it in. Thing is it starts right up and has amazing �hole shot� I guess it�s called lol. Purrs like a kitten all the way to 4400 rpms. When I give it full throttle and let go of the handle, it slides back about 1/2� but remains at 4400 rpms. Was hoping the linkage might just need adjusting.

Linkage doesn�t fall out of adjustment from sitting, unused.

I�d advise to NOT run the motor until the issue is resolved.

I had a Yamaha that did something similar. It needed all filters (four of them) changed and the injectors thiuroughly cleaned. Runs excellently now. A lean cylinder, from a sputtering injector, has VERY EXPENSIVE results.

Thanks for the advice guys. Looks like a check up is in its near future.