Check RAVE Valves

I have a 2002 Sea-Doo GTX DI, It ran perfectly, and then I winterized it, and, after taking it out of storage, it lost approximately 5 mph. The engine only gets to 4000 rpm until its been run across the lake, then it loosens up and reaches 5500rpm. weird. Do you have any ideas? Do the exhaust ports need to be cleaned every so often?
Chris

Chris,
Sea-Doo recommends annual cleaning of the RAVE valve guillotine to remove carbon build up. But a bad water regulator valve, low fuel pressure or a jet-pump problem can also cause this problem.
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