Idling Issues - Holley Carburetor

Very likely, the secondary stop screw is waaay out of adjustment. Set it so that the secondary transition slots are juuuust visible with the secondaries closed, and then reset the primary idle mixture and curb idle adjustments again. It may take a couple of adjustments of this secondary stop screw to get things right.

And if you have a stock Mopar PCV, that can be part of the problem; some of them let in too much air at the higher idle vacuum levels. What cam do you have, and what is your normal idle vacuum level? (But since the old carb idled OK, this my not be any issue.)