I was out on the lake today when I turned to head back up the lake the engine chugged once then died. It started again but was running very rough and stalling. I haven't done anything different to the engine or changed any config. One second working awsome next chug and die. Finally got it home there is lots of fuel getting to the carbs, oil mix good, strong spark on all cylinders. Still it will start for a second runs rough and stall. Any ideas???