Even though there is plenty of oil in the reservoir and the filler cap and dip stick are secure, when operating close to max rpm's my 2000 Evinrude 15 HP 4 stroke, with less than 50 hours, slows to fast idle (2000 rpm) and will not exceed this speed. Apparently this is Evinrude's Low Oil Pressure Warning for this motor - no audible or visible warnings are given. If the motor is shut off for 10 minutes and then run for a short period of time at less than 1500 rpm to reset the warning system the motor will operate satisfactorily at higher than idle speed for a short period of time then problem recurs. The oil and filter plus plugs have been changed twice this year and problem persists. Plenty of gas is getting to the motor as bulb is hard and motor will run indefinitely at idle speed when problem occurs. I'm at my wits end!!