1992 Chevy S-10 carb choke adj.

Should the butterfly always be closed or should it open when the engine has run for a while.I know on old carbs you adj the choke butterfly when the eng is cold and it will open as the car warms up. I am not familiar with this set-up, 2 barrel carb.
this one stays closed all the time except when rev'd up.

The engine normally started with just a turn of the key. Now the gas pedal must be held to the floor to get the engine to start once started it runs fine.

Appreciate any help, lost my job and trying to keep things running on my own.
Thanks