take off the coupler and blow into the line that goes back inside the intake manifold and make sure it's flowing fine. Try to blow and suck the line that goes to the BOV. You might be able to create enough vacum to feel the BOV open.
Otherwise if you don't, remove bov and try to compress the valve with your hand and see if it moves at all. Could be stuck.
Otherwise if you don't, remove bov and try to compress the valve with your hand and see if it moves at all. Could be stuck.