newbie question

I recently pruchased a '01 Yamaha 1200xlt. It runs great and really gets out on the water, very impressed!

The question i have is i am experiencing almost a misfire or break up at 3000 rpm i guess it is. It runs fine at any other rpm but from 3 to 4. It also runs a slight bit rough at idle. What are your thoughts on that. . . .Any thoughts?

I was also wondering what is the life expectancy in hours are these machines?

Thanks so much for your help!