Re: engine sputtering on takeoff
3 hours of trolling can load you up with unburned oil, carbon, whatever, if that's all it is, you're good to go. Maybe think about a decarb (see "Engine FAQs").
End of last season, did you treat the gas for storage, or else drain the carbs?
Any other symptoms at all? Starts hot or cold, idles in gear or out, acceleration, cruise?
If carbs are gummed up from a long winter with untreated gas, you have the possibility of partially clogged jets, results in running lean => higher than normal combustion temps.
Lean condition can often be diagnosed from spark plug appearance as a white or gray insulator. If the ends of your carb bowl drain plugs are discolored, it's an indication of varnish left behind by old gasoline.
Myself, I'd contemplate a carb rebuild anyway - she just always seems happier with fresh carbs. Plus which, there's way worse ways to spend an afternoon.
If I sound indecisive, it's cause I am - maybe somebody else will jump in with 2nd opinion.
