Have you adjusted the idle fuel mixtures on both outboard carbs. yet? If not do that next, the idle mixture screws may have lead covers on them, there in the bases under the fuel bowls
I set my stock outboard carbs. up from 1/4 to 1/2 turn out from gently closed all the way
BTW, I'm assuming you have new Holley replacement carbs. and not some other brand, do you?
Let us know what you find, that will help others on here later