I have a 1999 seadoo GSX waverunner. It starts and runs perfect below about 5,000 RPM. When I hold the throttle all the way open it revs up to about 5,000 then cuts out and sputters for 2 seconds. Then it revs up to 5,000 RPM again and cuts out again. As long as i hold the throttle down it will continue surging like that. Anyone know whats wrong?