fired up motor for 1st time, seemed to run ok, but would not idle, had to keep throttle up a little. when i looked in tank of water i was using for test there was blacks spots floating on the surface, obviously oil but is there anything i can do. What is the gap for the plugs on this and what is the best type of plugs to use? are these motors easy to flood, after it ran for about 5-7 minutes i could not get it started again? help and thanks