How are your valve covers set up with the PCV unit? If you are running one without any baffling, thats a big source of vacuum to pull oil through. On some aftermarket covers, the valve is right over a rocker arm. Need to be diligent on the baffling, even on cast covers. The cast covers sometimes provide a baffle plate but it can be improved upon. Stamped steel or aluminum a/m units generally have no baffling. I found that out on my Duster when I put chrome Moroso covers on years ago. No baffling and the valve was right over a rocker.