your biggest problem is not enough ignition timing.
advance the timing at idle to 15 degrees then plug the vacuum advance into a manifold vacuum source. timing should come up to around 30 degrees at idle with the vacuum advance connected.
then turn the idle down to 900 rpms and adjust the idle mixture screws for best idle (highest vacuum and highest idle).
More timing increases the rpms at idle which allows the throttle blades to be closed further which will put the carb back into the idle circuit.