It stalls occasionally, and according to my wife, only at idle (usually when coming to a stop). I suspect the IAC, and have taken it off and try to check it. There is 12V at the harness (with the key on); and 11k ohms on the solenoid, which Haynes says is correct. That's as far as their diagnostic goes, but since there's 12V available I should think when I plug it in I should see the shaft move, but it doesn't. I want to know if it should b4 I spend $100 on a new one. BTW, the interior was 'sooty', but the shaft was free to move, spring was ok, and I tried to clean it up. Next day or so will tell if it acts the same, or better.

I don't know about here in the Windstar Forum there are posts specifically for the IAC, but I know there are posts on this in the Taurus Forum. From memory, to test if the IAC is operating properly, start it, then with foot off pedal, turn steering wheel stop to stop. If it acts ok, not trying to stall, then the IAC is ok. IF it stalls or near stalls, then it's not working as it should. Another electrical test in addition to what you did is to measure from the disconnected pins at the IAC to its metal body for resistance to be sure it isn't shorting out. You should have 10k ohms or more. Your other readings and tests were right on.

Does it behave the same wether the engine is hot or cold?
Does the van idle OK in Park or Neutral? And does it change when you put it in gear? Any difference in idle while the brake pedal is depressed or released with the vehicle stopped?