I have a 8hp Johnson 2 stoke outboard that starts ok, but does not seem to me like it every runs at top speed. It does not foul plugs often,but when I take them out they always look fouled. From what I have read I might need to lean down my fuel/air mixture. Do you do this while the engine is running and if so do you do it at wide open throttle or while idiling? Thanks for any help.