03 Yamaha F-225 shuts off at idle or low rpm's

I have a totally rebuilt 2003 F-225 (lower unit, mid-section, engine) Both fuel pumps are brand new and also have new fuel lines and filters. after running the boat a while it will chug and shut off at idle speed or *****ing speeds (5 mph or less). I can pump the primer bulb and it will start right back up and run fine. It also does this after running for a while then shutting down to anchor and fish. Two different repair shops (Yamaha Certified) can't figure it out. Anyone ever heard of this? Any help would be appreciated.

Thanks,
Rob S.

[boats.net]

Does it have the vapor recorvery system installed on it? It will be a square plastic tank in lower engine cover at rear of engine.

Similar problem

I have similar problem. Motor works fine at rpms above 1000. However, when I get below that the rpm will drop to around 500 and the engine will sputter and die. I have been told it is a carb problem. I have disassembled the carb and sprayed cleaner through all the valves, but the problem persists. Not sure how to proceed.