Can you pull the PCV out of the grommet? If so, just pull it out and have someone start the car. Put your finger over the end of it and see if you feel it sucking a vacuum. If not, remove the valve and shake it. If it rattles, that's good, if not, replace it. You might want to pull the hose and see if there's any carbon build up in it. Clean it out if possible, if not, replace it.