Yamaha 150 four-stroke rpm issue

[carl sastram]

I have a 2005 Yamaha TXR150 four stroke (on a 20005 Sea pro 220 wa) and I'm experiencing something odd. When I begin a trip I can turn 5000 rpm at wide open throttle. Then after a few minutes the rpms slowly drop (while still at full throttle) usually settling in at around 4400, sometimes as low as 4000. I checked the plugs to see if any were fouled and they were ok. Any insight or help would be much appreciated.

FYI... I'm in the northeast so Ethanol is an issue, but I add Stabil in every fill-up.

[mitch]

give your vst a service and clean the filter inside on the high pressure pump