Throttle issues during cold weather - 1994 C1500 4.3L V6 TBI

I have a 1994 Chevy C1500, 4.3L V6 TBI. On cold nights - only at night, like it really matters - I have trouble with slow or no throttle response. It’ll drive fine for the first few miles, then when I give it gas she doesn’t respond. Most times, revs won’t change and it seems to run rich. Tonight it stalled twice when I gave it gas - two seperate times, not right after each other. A few times it has backfired when under throttle - again with no change in revs. Most times it will take mashing the throttle all the way down, then a short wait before it gives any response - sometimes not even full throttle even though it’s wide open. It seems to happen less when I shift into D instead of D(overdrive) - could this be a tranny issue? The throttle cable is tight and the injectors are clear and functioning as is the rest of the delivery system. Also, I noticed that there’s a butterfly valve inside the intake tubing - a small tube couples directly underneath this valve, but doesn’t attach anywhere else - could this valve be part of the issue? ie - airflow problems. Is this butterfly part of the stock intake? Does anyone have a fix for this problem? Sorry if I got a seperate question in there. Thanks for the help.

bump - I’m bumping this up so it get’s back to a more “seeable” queue position