Problem with choke not closing--butterfly valve not closing when I push pedal once on startup.

First check if the choke closes freely by hand. If it doesn't or is real sluggish, spray some brake parts cleaner on the ends of the shaft that go through the air horn, then work the valve back and forth to wash the gunk out.

I can't remember what kind of setup they had. I never owned an AFB. If it has the black plastic disc on the passenger side, about 2" in diameter, that has a wound-up thermostatic spring inside and one end of it likely is disconnected or snapped off. The clue is the choke plate would move freely by hand and flop around. If you have the metal housing that bolts to the intake manifold, that has a thermostatic spring too under that housing. I never saw one of those break but there is a hole on the side and inside that is a shaft with a slot on the end. That is to turn the spring with a screwdriver to adjust it. Most of those had a nut to tighten that shaft on the side of the housing closest to the carburetor. If that nut is loose the shaft will turn instead of putting pressure on the link to close the choke. That's a matter of turning the shaft to adjust the choke, and holding it there with the screwdriver while you tighten the nut with a wrench. Don't put a lot of twisting pressure on the screwdriver. That is not really a bolt or screw. It's a light-duty shaft with a cut in the middle and too much pressure will spread it open and usually will snap it apart.

Just so we don't overlook anything stupid, by '76 the cars and most trucks had electric heaters to assist the chokes. If you turn on the ignition switch before you start the engine, as in to listen to the radio for a while, that heater will be on and the choke is supposed to be fully open within three minutes. That will make for hard starting since the base of the carburetor isn't warmed up yet.

You get one or the other. When you have that black disc there is no choke spring housing in the intake manifold.

There is a linkage hanging down between the carburetor and that disc. You'll see it move up and down when you work the valve by hand. Most likely something came apart inside the disc. There's three screws around the outside of it to remove, then you can take that unit off and look at the spring inside to see what's not working.