OMC 4.3 stalling problem

[Tlong213]

After taking my boat out of storage after sitting for a couple years I replaced the fuel, fuel filter, plugs, wires, rotor, dist cap, and did a rebuild and cleaning of the carb. Boat starts up on first try every time and runs great out of the gate. After running on plane for 10-20 minutes when I begin to slow down close to idle the engine dies on me and won't restart for at least a half hour. Engine is getting fuel so no vapor lock. Could the carb be not adjusted properly? Flooding maybe? Any help would be greatly appreciated!