Jes if you have TWO hoses going into the valve cover one of them is for clean air into the engine and the other should be the pcv. BOTH hoses need to be taken off and reamed out and cleaned inside as either may have crud in them stopping the air flow.
The most common visable leak from blowby is the rear main seal. Small amounts in the aircleaner are usuall from the hoses or pcv.
In bad blowby cases I have taken out the pcv and connected BOTH valve cover hoses to positive vacuume.. This has stopped oil leaks for me in the past.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />