[JB34]

Davidlee, I had the same problem that you do. I have a 302 with a healthy cam, stage 3 porting on the heads, a Victor Jr. and too big a carb...Holley 750. I messed around with this thing until I finally broke down and called the Holley tech line. It was a simple fix and I felt like a chump for waiting so long to call.
1.) check your float levels; when correct,
2.) set your idle mixture at all 4 corners.
3.) use the proper power valve Don't assume. Take your vacuum pressure at idle divided by 2 ( your avg is 17 so use an 8.5 power valve)
4.) check the clearance on the accelerator pump lever to the adjusting screw. This needs to have a .015" clearance so that your pump diaphram is not stretched too far. There is an adjustment screw with a spring and lock nut.
5.) Go to a larger pump shot on the primary!!! AS it is stumbling this is the final answer. You will need to jump three sizes to see any difference. Try a 35 or 37 and I bet your problem will go away.

Mine did; hope it works for you.