Had almost the same problem with cast Aluminum covers. Was using PCV on passengers side and open breather on drivers side. My car would suck
oil from the PCV valve and burn it but only after the engine got hot. The problem is the baffling. These covers are not so good, and if you run high volume
oil pump and roller rockers it's even worse. I put on Ford Motorsports covers and have had no problems since. Plan to copy the baffles in the Motorsports covers and tig weld some aluminum copys into my cast covers.
Rene'