If it is a ox66 150 it sounds like a oxegen sensor I had to put 3 on my 2000 150, was told it was a weak point on that motor. water in the gas will knock them out. If it is the carb version sounds like a fuel pump, I had a friend with a 99 200 carberated motor and he also had a similar problem it wound up being somthing in the fuel pump.
Hope this might give you some place to start.