Runs great than dies

hi all i finally got my 151a m

hi all i finally got my 151a motor replaced but now i have a new problem the engine starts and runs great go out run for about 30 min runs fine on my back to the dock at low speed it dies??? than i restart give it some throttle clear it out than dies again seem to be flooding out ???? im at the end of my rope this year please any help??
replaced engine block reused my head cam exc replaced timing belt checked it its perfect have a hotspark ign excel coil (new) cap good wires good
plugs good no backfire through carbs good
just stumped

"I would try to adjust the idl

"I would try to adjust the idle mixture and idle speed, then synchronize the carbs."

"I was told by a mech earlier

"I was told by a mech earlier this year (when I still had Solex carbs ) that the needle/seat valve can cause symptoms like yours if the unit is sticking. What happens is the rising float does not totally turn off the flow of fuel to the bowl and, at idle rpms, it floods over. At high rpm an open needle/seat valve is a normal situation. Worth while checking."