I spoke with Damon at Diamondback Engines in Texas who is the current foremost authority on these intakes. He told me to put a 1" 4 hole spacer under each carb. That made a huge difference.
Next he said to put a 1/4 " spacer between the lid and the bottom to increase the radious the fuel has to turn in due to it just slams into the bottom of the plenium. I never did that cause the spacers cured my drivablity issues.

Call him and pick his brain. Very smart man.

Thats my 10 cents.