[Phantom]

I'm not sure how the Throttle body (TB) is set up on your car but there should be an idle air stop screw, the screw will adjust how far back the TB plate will close since the arm the throttle cable if connected to rests on the screw.

With this you have two options tighten or loosen it.
If you tighten it the TB plate will not close as much this can help your stalling problem when cold and a 1/4 turn might be all it needs, but this will slightly raise the idle speed as the TB will let more air in at 0% throttle.
You could loosen the screw (possibly) and that will close the TB more with 0% throttle. That could make the stalling problem a little worse but as you said that could be fixed by making the popcan hole larger. The good thing with this is it can slightly drop the idle speed at all temps after correction has ended. One issue that could come with this is the TB plate might stick a little when starting the car cold but a small turn of the screw can correct that if you backed it out to much.