Often carb problems, aren't carb problems.
What you might try, is see where the timing is at to start with. Initial, total and how the vac adv is hooked up- whether to ported or manifold vac.
Once that is straightened out, set the idle mixture screws w/a vac gage if possible, otherwise to the best idle speed w/both needles about (within 1/2 turn at the most) the same distance out.
Not until this is done, can any real attempt at tuning the carb can be done, although a lucky guess might pick out the problem from the possibilities.
Like float level, fuel pump, vac leaks, warped castings, incorrect power piston spring, jetting rods, secondary air valve setting etc.
If you just want to try something EZ- take a can of carb cleaner to it, following the can directions. It may loosen/clean the air bleeds and orifices enough to straighten it out.
Tighten (but don't OVER tighten the carb bolts. The 2 front bolts go all the way through the carb so be careful. Check that the screws securing the airhorn (and throttle body- but you need to pull the carb) for tightness.
Make sure the float is ABSOLUTELY not closing on you while the engine's running.
Let us know.