So let's get some things clear.
You have an AVS on a ThermoQuad intake? Is this correct?
You have an adapter to run said square bore carb on a spread bore intake?
That's almost always a bad thing, and I've done enough testing to know that a spacer isn't always a good thing. In fact, most of the time it's a loser.
The number ONE issue with the problem you have is easily corrected.
You need to pull the intake, and buy a gasket that blocks the exhaust crossover that goes from one head to the other right under the intake manifold.
There is no reason to leave all that heat going across there. Unless you think you need a choke. I haven't used a choke since 1982. Of course, you could still use an electric choke if you feel the need for it.
That said, you can't run all that heat under the carb like that and expect any carb to be happy about it.
Block the heat crossover and it will help everything.
