Rough Idling and dies when weather gets cold

[camoit]

I would say setting the screws from a closed butterfly is the best starting point.
If you know where the screws are you can look and see how she works.
One screw controls the speed of the engine when hot. the other one when it's cold and the choke is closed. The throttle opening adjusting screw works with the secondary or choke. It will determine at what vacuum the secondary or choke move. I can't remember of the top of my head. But if you look at it's fairly straight forward on how it does it's thing. You just fallow the vacuum bore holes and linkage.

As for the PCV it works as a regulated vacuum leek and has caused many strange idle problems. After that comes the EGR valve stuck. It can be checked by disconnecting and plugging the hoses from it. Then connect a hose on the diaphram of the EGR and pull a vacuum. Confirm movement of the shaft. Engine will run like crap.
Let off the vacuum engine runs better. EGR, OK..

NOTE: Early years,, Some carburetors came with a slide ding-A-ling in it. It would need to be pulled at the same time you are sucking on a vacuum hose of the EGR.

Thats because exhaust gas, is also controlled by the carb as well.
Of course back then we had to show the smog guy how to properly check the EGR. They swore it was broken. But they could fix in a day, or so they would tell you.
Now you would proceed to hold there hand and show them how the carb worked. The light would come on in the projector of a brain they had. And low and behold like some magic trick they had never seen before it worked, just the way they were taught in state smog school.