Having some difficulty with at Idle and low rpms? Once I get the rpm's up the boat runs like hell, but at idle and low rpm's the boat stalls out after about 15 seconds. I can get it to go if as soon as it starts I put it in gear and give it some throttle. I checked the fuel and the primer ball is hard and there is fuel getting to the outboard. I am thinking maybe needs a carb cleaning? Any ideas?