OK. There is a fast idle adjustment screw that should open the throttle plate when the choke is pulled and increase the idle speed. Maybe this needs adjustment. Screw it in to increase the fast idle speed.
There are two vacuum actuators that are supposed to open the choke plate (1) once the engine gets hot and (2) just after the engine starts to prevent too rich a mixture. Both these vacuum actuators are connected to linkage on the firewall side of the carburetor. I think there is also mechanical linkage to open the choke if the throttle is opened all the way.
descriptions and troubleshooting of these functions are in the factory emissions manual. Check it out.