Holley/Demon Carb stumble

BTW, those stepped boosters were designed to 'bust' the fuel up into a finer particle.
The 'step' creates a low pressure area that the fuel is happy to fill the entire 360° of the step, once it does, it shears into the air stream in the form of smaller droplets.

Beings that you're not experiencing this 'busting of fuel', it offers proof of a carb being too large. There's simply not enough velocity maintained for it to function properly.
I know you've been kinda beat over the head with this... I'm sorry.