There is a screw that controls the "fast idle" on your carbs. The end of it
should just (or almost) touch the fast idle cam when the choke is completely
pushed in and as you pull the choke, the cam should push on the end of the
screw to make the throttle open gradually. The fact that you have to step on
the gas to keep it running means that you are not getting (enough) fast idle
engagement.

Being on the lean side to start with is tolerable in warm weather and many run
that way in the summer as an economy measure. But in winter it makes things
pretty hard. If your plugs look "too clean" you may be "too lean" and a couple
flats richer will probably also help in starting.

Plus what all the other guys said. Your electrical system should be at LEAST
13.5 volts at a speed somewhat above idle, no matter what kind of charging
system you have. 14 volts would be better, especially in the winter.

Usually with everything in good tune and carb float bowls full, the engine should
fire and start in not more than 3-5 revolutions, more if it is cranking slowly.
--
George Downs, Bartlesville, Heart of the USA!