When you say hooking the breather up to PVC port on carb , most breathers are hooked to the air cleaner housing.unless the breather has a proper working PCV valve in it . If not don't you have a open port..Maybe try putting a PCV valve with rubber grommet in one valve cover and the other side breather to air cleaner housing and see if it does better. This is a waste of time if the engine will not idle wright with no breathers and all PCV ports plugged. Just thinking out loud