That sounds more like a vacuum line problem than anything else. The lines from the breathers to the throttle body are your likely culprit. It is common for them to dry rot. You hear a lot less of this from owners with cold air intakes and catch cans since the NeedsWings kits replace the hard rubber lines with flexible rubber hose.

The easy way to check your lines is to spray soapy water over them. Any bubbles will indicate the fault. A visual inspection might even turn up oil near the connections to the breather covers. Try getting some hose and screw clamps from the local parts store, much easier and cheaper than finding the OEM lines again.....unless you're a hardcore purist.