Spark plug in cylinder 4 is fouling. Could it be attributable to bad PCV Valve? How do i check and clean PCV Valve? Can you run car with rubber plug replacing PCV Valve to determine fouling cause?

I doubt that the PCV is causing the fouled plug. The PCV is just a one way valve. Shake it, can you hear it rattle, good. Now blow in each end. Blowing in one end will be impossible but the other end should free flow. If it's blocked either soak it in lacquer thinner or buy a new one.

Thanks! man!!

PCV issues would affect all cyls not just one.