My '97 760 wave venture will no longer reach top speed. The problem began when i was towing a friend on water skis (170lbs) and now the ski will only go about 15mph full throttle. I did a compression test and the compression was right where it needed to be on both cylinders. The engine still tacs out the same as it did before too but now the block seems to have a minor shake when it is tacked out. Maybe it has something to do with the impeller? Any help or insight would be greatly appreciated. The ski only has 60hrs on it too. Thanks