03 70 horse 2 stroke problem

I just bought fish hawk 1650 with a 03 70 horse 2 stroke engine, it has pretty much sat for the past 2 years. My problems are i am only seeing around 3200 rpm at WOT, the boat will plane out and run about 35 mph, the previous owner said I should see about 43 mph, and at idle it the tach will read about 800 rpm, so the tach has to be set correct, right? Also when idling it is not very smooth and quiet I know it is still a 2 stroke but it seems like it should idle down nicer than what it does, any thoughts would be appreciated.

[boats.net]

If been sitting that long I would have carbs and fuel system cleaned.