Help me get the off-idle stumble out of my QF 750-AN Double Pumper

I have a quick fuel super street series 680cfm vaccum secondary carburetor and I had the same problem, maybe I can help you out.
First thing to do is make sure there is no slack in your accelerator pump arm, (the bolt and nut) At wide open throttle make sure there is at least .015 clearance, you can use a feeler gauge to check, this way the diaphragm does not bottom out.
Next thing to do would to be increase your accelerator pump discharge nozzle size, you said it has a .031 on it now, try a .033 and a .035, I run a .035 in mine with the hi-flow hollow screw. Next thing you can try is changing the pump cam, But without knowing what color pump cam you have now I can't give you a recommendation.
Mine likes the white pump in the number 1 hole, The white and orange and red pump cams have a more aggressive shot of fuel right off idle.
Another thing you can do is decrease the size of your idle air bleeds, you said it has .069 iab's in it now, you could try some .065's and re-set your mixture screws and see what happens. Another important question I forgot to ask... Where is your float level? These are some different things you can do to ry and tune out a bo, but it's not everything. There are idle feed restrictors in the metering block that can be increased as well. but we need to determine if this is an accelerator pump problem or a transision circuit problem.
Try the nozzles and the pump cams first, if that don't work let me know and i'll do my best to walk you thru this.