Ported vacuum. Slow throttle is where it bogs most consistently. My method for getting it running is putting it in drive, letting it creep forward in drive, and then giving it some quick throttle to rev it. Once there I can drive until I have to stop again.
It never dies when I give it throttle while in park. Slight tilt of the throttle revs it nicely. It’s only once in drive and given throttle that it happens. Someone mentioned torque converter, but it doesn’t mind being in drive, creeps forward easily, and then dies when given light throttle.
I’ve had initial timing from 12’ to 35’! I know 35 isn’t good, and the starter chugs hard, but when at 30’ initial it doesn’t die at throttle application.
No vacuum leaks that I can find spraying all around the engine, carb, and vacuum tubes with carb spray.