The motor looses power about once every outing. Doesn't seem to matter if at idle or full power.When powered back after the cough, it tries to choke itself out. I can get it to run by letting it idle it's way through the problem, with a little throttle play, or sometimes even giving full power to blow through the rough running. Once it goes through it, it usually doesn't repeat on that outing. I have replaced plugs every year and water separator as part of the routine winterization work,with no effect. Please help if you can.