Yamaha - hard starting

[<Minnesota>]

I have a 20' pontoon with a Yamaha 40 - 4 stroke (new in 2002). Been happy as a kitten with the setup so far, however, the Yamaha is starting to give me some issues. It is becoming hard to start - I have to advance the throttle on cranking for it to 'catch', and it will run rough for about five minutes while warming up. After warm up, it will run fine at low to mid throttle settings, but on the upper end it will occasionally load up and lose power. If I reduce power and go back up it will be fine for a while. I add Yamaha's fuel additive and STABIL on all fuel fills.
Any ideas before I pull it out and trailer it 100 miles to a mechanic? (our season is too short!)

[<boats.net>]

It sounds like carb trouble possible need to have carbs cleaned