347 oil consumption or pressure problems

If you run a breather on the valve cover you must run a breather where the pcv valve is and cap off the line to the upper intake. The way you're running now is probably the cause of your idle problems due to the unmonitored air. Basically, right now your car has a major vacuum leak...

Do you run baffles in the valve covers? Running a HV pump makes it worse also because they pump so much oil to the top. It can be a hard thing to get under control. I made special baffles for my valve covers that come up close to the breather when installed so you have less splashing inside the breather. Served the purpose for a while, just got an occasional drip from them. This year I switched to a header evac system. Works great. No more problems. I agree with Blandnuts also - disconnect the pvc and plug it off. You're probably pulling straight oil through it anyway. Run the crankcase open and make provisions to stop the oil splashing or get an evac system. Note also I've seen baffled grommets made by Mr Gasket but they seem too restrictive to me. If you're running an open crankcase you don't want to restrict the flow out of the breathers very much.

Header evac consists of two 45 degree pcs of threaded pipe basically that you weld into the header collectors. They have one way check valves that you install inline and they connect to special valve cover breathers that have a hose connection. The exhaust gases rushing by the collector inserts draws a vacuum at the breathers. You'd be surprised how much they pull. With the engine idling, if you pull out a breather you can feel the suction on the breather. I'm sure at high rpms it really draws. Impressive system especially when you look at the cost. It's cheap.