Mercury 25HP EFI 2006 model

[skeeter256]

Hey guys,

Having an intermittent issue on my 25HP that I'm kind of scratching my head on.

Motor will start fine, idle fine and run fine, for the first say 3-4 hours of the day, regardless of whether I'm just idling around, or doing some running at WOT. Then it starts "bogging down" on me. Example...Saturday did some idling, some running , at about hour 4 went to make a run and starts bogging down. AT WOT my boat goes 23 MPH, will be running along and it will start slowing down to 17-19 and even less. It will then get worse to the point where WOT is 7-8 mph and running real rough. Gets to the point where it starts, sputters, dies for a bit, and eventually it will slowly seem to get to where I can run 15,16,17 mph at WOT....but it never seems to get back to normal 23mph for the rest of the day.

I have done the following and no real noticeable improvement

Oil change
Lower unit oil change
New fuel filter
New thermostat

Impeller seems fine as the water discharge is strong at all times. this boat doesn't get used much, maybe 10 times a year and most of those trips are all idling . Hoping someone has dealt with a similar problem and can shed some light

Thanks!

[SilverFox579]

Is this a 4 stroke? Mercury - 4 Stroke / Verado