idle problem with long duration cam

Moper is right about why it pulls down when in drive. Also that is a long cam..you need 10.0 min. compression with that cam. You didn't mention yours. That is the first thing I think about when we complain about drivability with long cams. And what vacuum is it pulling in drive at idle? If less than 6 or 7..you don't have enough compression (for good carb signal). If you use that cam with your combo..might want to consider a vacuum sec. 3310 Holley. It WILL improve drivability. Terry.