[1] Pretty sure the Blaster 2 requires a 0.8 ohm bal res. Stock is 0.5 ohm. However, I doubt this is the problem, though possible.
[2] Vac adv. Is it connected? If yes: every time it operates, it flexes the p/up wires & eventually they break. This could explain why it fires up ok after stalling: wires have moved & contact has been restored. To test: disconnect 2 pin socket; measure resistance while wiggling wires; should be 100-400 ohms.
[3] Whistle; while it is whistling, dribble some engine oil onto the t/shaft & see it the noise changes. To confirm where the air leak is.
[4] I would p*ss off the Holley & fit a Edel 625 AFB or AVS2.