2003 Johnson 150--Won't idle??

A friend of mine just decided to get the family boat back in the water after 2 years in the garage. If he starts it and gives it a little throttle, it will continue to run but, when he puts it in gear, it runs like a dead dog. If he nurses, with the choke, up to 10-12 mph, from 10 to maximum mph, about 42, he says it runs great.
Any idea what he start lookin' at first??? http://www.bassboatcentral.com/smileys/doh.gif

Drain the carb bowls and gas tank and start from scratch with new fuel.

Thanks Fred. I believe he's gonna start on it tonight.