Well, on my truck ('82, with 22R motor) the choke is electric, it's a round housing that is on the back of the carburetor, towards the rear of the truck.
The choke housing contains a metal spring (round coil) which, when cools, is supposed to pull the choke place closed. This thing is called "choke thermostat". When it warms up, it lets the choke plate stay open. The spring has a lip that engages the choke lever and thus controls the choke plate.
The problem with my truck is that the choke opens too quickly, after the engine warms up somewhat, but not enough to idle at low speed (700rpm).
Another issue is that the lip on the heat sensitive spring sometimes jumps off of the choke lever, so the lip on the spring is either worn, or needs to be (carefully) bent... I just watched it jump off of the choke lever this morning...
First thing, I would take the air filter off (engine off and cold) and gently try to move the choke plate... it will either have a springy feel to it, wanting to close, or just flap around (like mine does). Flap around = not good.
I am considering replacing this "automatic choke" with a manual choke from Napa. I think it would be a simple and elegant solution.