Vacuum leaks
Look at your rubber vacuum hoses (they are about 1/4 - 3/8 inches in diameter, if they are dry rotted or cracked, replace them. IF they slip on/off of their connectors too easily, they may have stretched out a little bit, cut the ends off, and put them back on.
You may listen for a leak. Sometimes using a cut off piece of garden hose is a good aid to listen with. Sometimes a cardboard tube (like from gift wrapping paper) is helpful. Just remember that whenever you stick your head inside a running engine compartment, that you are not wearing any loose clothing or jewelry that can get caught.
Another suggestion is to use a spray can of carb cleaner and spray around the bottom of the intake manifold, and the base of the throttle body assembly. IF there is a leak, you should hear a change in your engine.
Choke adjustment
It's been 30 years since I adjusted a choke. The best that I recall is that there is a black plastic cap/cover held in place by two or three screws, on the carburetor. They usually have little index markings on them. They are usually about 1 1/2 inches in diameter. There is a coiled spring within that plastic housing (like a coiled thermometer) that expands as it gets hot and opens your choke more and more. When it gets cold, it shrinks and closes the choke more and more. To adjust it, wait for your engine to be cold. Then mark the original location of the cap. Then loosen the screws (a turn or two), and rotate the black plastic so that the choke *just* fully closes. Tighten the screws and you should be done. You may want to check it to make sure that it is fully open when the engine is hot.
Generally speaking, to start a carbureted engine, one should fully depress the gas pedal once, fully release it and then depress the pedal half-way.
