Engine runs at a higher RPM but doesn’t idle – possible causes?

So, I decided to put a completely new carburetor on my 383 instead of trying to repair my junk original Carter 2 barrel. I got the same model, albeit from a 1969 model, but it's still pretty much the exact same type of carburetor and bolted right on. It was an ACDelco rebuild, I adjusted the idle screws to 1 and a 1/2 turns and tried to adjust it: it doesn't want to run at all at the idle RPM, but if I rev it it fairs a bit better.

I've heard several suggestions from elsewhere and on...

Engine runs at a higher RPM but doesn't idle - possible causes?
Author: EurekaSevven