pcv valve???

What is your question?

I have a 99 dodge caravan that recently started having an extremely rough idle. It often feels as if it is going to stall, but it catches itself and does not stall. If I slide it from drive into neutral it runs extremely smooth. It drive fine except when traveling at 40-45mph in which it shutters until i get it out of that speed range or release the gas. There is an good amount amount of oil going into the air filter compartment. I have changed all spark pluds, distributer cap, rotor, and fuel filter.