RE: low idle @cold start
Hi John, What year is your Explorer?
I had purchased a used 1998 that was doing what yours is, and when I went to the dealer, I learned there was a recall for the head gasket.
There was a heater switch, or something like that, I think, that was taken care of also.
But that switch was not the cold start up problem, the head gasket was.
And I did get a new spare tire because it was a firestone.
I had them replace every hose, belt, and clamp while they were in there replacing the head gasket.
I see there are a few posts around here, that sound like the same problem?