Did you happen to see if the IAC was at max open already? If it needed more air and the IAC was already fully opened, that could be the issue. With the truck warmed up and idling it should be at around 5% so it has sufficient range to maintain idle when it's cold.What about moist air could keep this from idling?
When I held it at 2-3% throttle, it would run. But letting off it died.
I would have thought the cool moist air would be too much oxygen if anything.
But it acted like not enough.
Maybe it was a coincidence and the IAC solenoid was stuck..
But I tried it multiple times.
Then today it starts right up and idles.
Thinking back, it's done this once before, and I think it was raining then too.