i have a 93 blaster with riva water box, solas impeller, cauffmann pipe, protec head so on.. the ski runs mint but for one thing. after a little riding the ski acts as if its rpms wont go past say 3500 4500 outa say 7000. while happening if i get the back to leap outa the water it'll rev normal for a bit then if i get off the throttle itll it do it again. ski never seen salt water, electric box has no green n all wires are good, carbs are clean..what the hell could it be?? thanks for any and all help