Hey, I woud first check the Jets. I have messed with AFB's, AVS' on my 71 440 cuda in the stock class.....Typically the new afbs/avs/edelbrocks come way over jetted. With the bigger cam you run, idle screws are not so important...crank them out so it idles decent. THey quit working anyway once you give it some gas...
IF you run Qt mile or street, how do the plugs look after a run?

I would keep 4 side square on jet size. They seem to run better that way....Curious to see what you jet sizes are right now....I have some base figures on jet sizes I can give you (from experience)

If the car runs great otherwise on the street, plugs look good--you can fatten the metering rods so it decreases the jet size hole at idel...those lift out of the hole as well once you hit the gas.....

If your plugs are jet black...probably too big of jet sizes...

I have gotten a puny 750 AVS to go 11.8 on my 440 with cast iron intake...

Let me know, Jeff.