Hey I just experienced the same problem on my 2002 GP800r.. I was cruising around at 30mph and hit a medium sized wake when this first occurred... After about 10 minutes of idling back at 7mph(if i gave it gas it would over rev) finally the problem sort of went away and I got back up to 41 mph before i eventually slowed to 25 and ran into a small wake and the problem came right back.. It would idle fine at 4-8 mph and when I gave it more gas it would start to over rev, so I had to idle the rest of the way back.. I really don't know too much about wave runners but I'm guessing It's something to do with the Pump Seal or the Impeller.. Any suggestions anyone?