I have a 40 hp yamaha outboard that won't idle or run good at slow speeds when in idle it runs about 15 seconds then shuts off at low speeds it sounds like it wants to bog but if you give it full throtle it will take off and run fine, back about a month ago I got some water in the gas at a country store once I narrowed it down I drained the tank .fuel lines and carb. I put good gas in it and unplugged the gas line and ran it till it ran out of gas but I stll have this problem can anybody help me thanks