My 06 SXR is acting funny, when I go out for a ride , its starts and idles fine, idle out to the bay maybe about 7 min. I ride the ski for 40 min, it runs great, then when I head back into the lagoon and go to idle in it does not want to idle, it stalls and I have to give it gas to keep it going, when I give it gas it will stumble and the clear out and run, but if I let off the gas it dies. What would cause this? Plugs look good, compression is 150ish in each hole, and spark is good.