After all the good work you've done, one possibility is that the throttle plate is closed a little too much when it's at the rest position. The engine will be most sensitive to this when it is cold and will act very much like it has a dirty throttle body, ie. cold stalling.

The throttle plate rest position is set with the little adjusting screw with the lock nut on it. Back the adjusting screw away from the stop plate, hold the throttle plate shut then advance the screw until it contacts the stop (just before it starts to push the plate open). Now advance the screw 1/4 turn more and lock the screw in place. Before you do all this make sure you've disconnected one end of the linkage control rod and loosened the throttle position switch (TPS). Afterwards you will need to re-adjust the TPS. The basic TPS adjustment can be made by holding the throttle plate shut and rotating the switch until you hear the click, continue until the switch cannot be turned further then tighten the screws. Just for good measure you should also check and adjust the linkage control rod, the gas pedal cable and downshift cable (for automatics). See the 700-900 FAQ for more info on all this.

As to your 2-wire IAC valve (the later type), it is supposed to look partially open at the rest position (it is actually in an over-center position beyond the closed position). A dirty/sticky/worn IAC could also be behind your problems, but I would expect it would affect warm stalling just as much or possibly more than cold stalling.

Re-check for air intake system vacuum leaks and disconnected or split hoses. Normally that'll give you an incorrect idle and rough running, but a rough running cold engine will stall more easily.

Hope that gives you some more to think about. I'm betting on the throttle plate.
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Dave -not to be confused with a real expert, just goofing around at this