Ski has about 80 hours on it. When you push the throttle all the way it seems like it is seriously bogged down topping out at about 4000 rpm's. After a while it kicks in and picks up speed and runs ok. As long as you keep it full throttle, it seems to run ok but if you get it below about 5000 rpm's it seems to lose power and go back in the bogged down mode. Any comments would be appreciated.