Check the PCV valve (A), the hoses (B), and their connections for leaks or restrictions.

Start the engine.

At idle, make sure there is a clicking sound from the PCV valve (A) when the hose (B) between the PCV valve and intake manifold is lightly pinched with your fingers or pliers.
If there is no clicking sound, check the O-rings for cracks or damage. If they are OK, replace the PCV valve and recheck.