Holley stumble trouble

The two orifices that is out of whack to me is the .053 IAB and the .024 MAB.
The .024 MAB delays the primary start, a .026 or .028 is what I run with 2 hole emulsion blocks.
The .053 IAB is normally .070 or .073 with today's carbs. On a 650 or 750 I run a .033 IFR and .067 or .070 IAB.
I believe your issue is a combo of to lean on idle/transition and slightly delayed primary coming in at light throttle. When you continue getting in the throttle the signal increases and primary have full flow.
Threaded brass set screws are the way to go if you really want to dial in. 6/32 x 1/8 for IFR, EML, MAB. 8/32 x 1/8 for IAB, PVRC, TSR.
Today's pump gas contains ethanol and it takes more fuel to equal the same BTUs real gasoline produces. Old carbs were setup for pure gasoline.