Some good advice above.

You could always try a New Power-Valve, but I doubt that is the problem.

It could be a bad gasket (like the baseplate-to-body) or a cracked baseplate.

If it has Internally-adjustable floats, have you checked the adjustment height? It may be suffering from low fuel level. That can cause problems as you describe.

Holley has lots and lots of great, FREE information at their website including instructional videos.

Holley Tech Library

Holley TV and Videos

You can also search YouTube for videos on Holley carb topics.

If all else fails, you could seek out a local performance-oriented carburetor repair/tuning shop, or worst case, buy a replacement carb.

Carb problems can be frustrating. Sometimes, there is more than one problem involved.