My 1996 GSX rpm's surge and drop about 800 (rpm's) when cruising at wide open throttle(roughly 6100 RPM). Obviously resulting in a brief power loss for a second or two. It will then go back to 6100 rpm's and will do the same thing. At 5300-5400 rpms the watercraft runs perfectly fine. Any thoughts on what the cause could be? I appreciate any ideas you may have. Thanks....