Idling Issues - Holley Carburetor

I'd disconnect and plug everything vacuum related on the carb. Isolate the intake tract. If the idle comes around, reattach each vacuum hose one at a time and see if idle changes. Look for the offender.

Is the large PCV plugged? Seen that one a lot!

Make sure none of the linkages are hanging up on the intake manifold. Look real close at the pass side secondary throttle shaft end.