Boat started losing power at the end of last summer (2015). Had carburetor rebuilt. This season we began by having fuel filter changed - but it still would not go fast. Had engine compression test and numbers were fine. Cleaned out air vent to gas tank. Tried running it with gas cap off - no luck. It doesn't stall, starts up every time. I Last guy told me he'd have to cut through the hull to access gas tank. Did not do that. Boat was put away in storage last week.

What else could this be? So frustrating. Any thoughts?