Had a 10th gen Corolla with leaking oil from the valve cover gasket and spark plug wells (onto the plugs). I replaced the valve cover gasket, which stopped the oil leak for a while, then it started up again. Replaced this pcv valve today ($6 at oem dealership), cleaned the throttle body, and replaced the intake manifold gasket.
Car runs smooth now. I put in new motor mounts, but there was still some rough running in the motor, but now there isn’t. I bought this car with 170k miles. It has 177k miles now. Don’t know how old this pcv is, but it looks like the original. Maybe the second. The spring inside is pretty weak and I did not have a check engine light before or after. It looks fairly oil fouled. No leak of valve gasket and smooth running car. The inside of the throttle body was black, cleaned with throttle body cleaner and a microfiber cloth.