I have done tons of work on small engines but I'm stuck on this one. I duck hunt in Oklahoma and I use this engine on my duck boat. It is currently duck season so I need help quick. First off I want to say that the boat has been running like a dream before this. No issues whatsoever. So the story is that we were wrapping up hunting for the weekend. We were in a cove and we're headed back to the boat dock. I throttled down once we were on open water and then the boat very slowly lost power and then shut off. The only way I have been able to run the boat since is if I start it at full throttle. It runs and sounds great when I have the throttle at full speed. As soon as I let off and allow it to go down to idle speed it stalls out. I have cleaned the carbs very well, checked compression at 120psi on all cylinders, all spark plugs are firing, fuel lines are new, gas is brand new, tried adjusting the lean screw and that didn't work, also tried adjusting the idle screw that didn't work. I have pulled apart the fuel pump and everything on it looks perfectly fine. I have no clue what else to do. Please help!!!! Sorry for he long post but I was trying to paint a picture for you.