Holley 80457-2 stumble

just a couple of ideas ; the vacuum sec. spring in that carb is black ,may need to be changed . the power valve in the kit was a 6.5 might want to run a 2 stage , I had to make these changes on my 80457-2

I don't think the vac spring and power valve affects the issue I am having.
But I will keep it in mind.