PVC breathers on valve covers

I put a stock type PCV on my 360 with a XE268H cam and my idle went up and I couldn't get it down. Also, when I would turn it off it would diesel really bad.

I even backed the idle speed adjustment screw on my Holley 750 DP all the way out so that the throttle blades are all the way closed. No luck there either.

I played with 4 corner idle adjustment screws and that helped, but then couldn't start the car when cold.

So, I took the PCV valve off and plugged the port on the Holley. Maybe I just need a different PCV valve or something.