mercury 15hp 2 stroke bogging down :(

[jay h]

hi there everyone i am new to these forums
i have a mercury 15hp usa model that seems to start fine, butdoesnt idle very well, when i start it up when its cold all is well and will get up on the plane normally, but as soon as it warms up it boggs down and will run very rough
please help me, this has been an ongoing issue and this motor has cost me in excess of around $350 and also have had the stator replaced ,new carby gaskets installed, new spark plugs

[boats.net]

Run a compression test, check for spark on all cylinders when engine is warm, remove and clean carbs and fuel pump.

[jayman]

bogging down

If you have good spark, spark advance, clean carb and good compression and now you are pulling your hair out! First run it with the cowling off so if you have an exhaust leak the carb can have some fresh air. If that changes nothing I have seen a lot of these motors when you troll a lot or use too much oil or poor quality oil the exhaust tube gets plugged up with carbon. The hole just gets smaller and smaller. I pull the gearcase and powerhead and scrape the carbon out of the exhaust. New gaskets, impeller because I am there anyway and good as new. good luck hope you find the problem.