360 magnum troubles

MOPAROFFICIAL said
That above, probably too advanced and the pump shot is or could definitely be too lite. and just a side note...what's been done to the heads?

Doubt it's too much but for sure check pump shot AND IDLE TRANSITION SLOTS

With the idle set up "best" remove the carb or look down with a bright penlight and see if the throttle blades are "in" the transition slot area

Here

holley transition slots

Also how did you set idle mixture?