96 550 floods after warmed up and shut off

96 550 cougar floods after warmed up and you shut it off and it sits for 5min or 2 hours the carbs have been cleaned four times new needle and seats also replaced needle and seats with some more new ones new floats
and new float levers and pins new fuel lines and filters and new fuel pump
but it runs perfect when riding it carbs all have the right jets and stuff in them any help thanks can the vacuume line for fuel pump suck fuel or let it leak to engine