your idle passage is clogged
I usually take an old brake cable, unspool ONE of the little braided wires, and run it through that tiny hole below the base of your venturi (look on the air filter side)
also, if you bored out your carb, and had to remove and reposition the emulsion tube, make sure the bottom hole in the tube lines up with that tiny hole i told you to clean, because if they don't, you won't idle.