Check all of your ignition components, first, including timing. Make sure your vacuum advance is working.
That said, the last time this happened to me, it turned out that the carburetor needed to be rebuilt. Since it was a FrankenCarter carb, I purchased a real rebuildable YF core and rebuilt it.
I believe the problem was the accelerator pump leaking or not working at all - I forget.
My experience with knockoff carbs is not good. Fake Autolite on '66 Mustang is horrible. I wish I had known how bad the modern knockoffs were before buying it.
