It sounds in this example, that the IAC valve is actually closing off at off idle speeds, or at least off idle when engine is hot. Ron Hatton liked to and taught us to do the Mod you did here to this IAC valve. One thing, though- Ron was in Phoenix Arizona at the time. Hot climate.
In any event, it sounds like this IAC is doing what it's supposed to, closing off when not needed.
Going out on a limb- we like anyone want to have and believe in One size fits all solutions to problems. Meaning you can restrict the IAC on any injected engine. And do it the same way to the same degree every time. But what worked for Ron in Phoenix, hasn't worked for Ultrashotone, and also didn't work for Karl back on Long Island. I'm tempted to think that this will be across the board w/ this. BUT, here's going out on the limb, w/ a guess or hunch...I remember Ford, back in the Eighties, had myriads of different Emissions equipment on their engines. I remember looking at emissions vacuum hose maps in big manuals, and there were often 5. 6 or more different emissions configurations/ hose routing setups for any one engine. The Vacuum Maps went on for pages...
Now, more recently, I recall researching about the PCV systems for Triton and smaller 4 cyl. Fords, in the current OBDII time. There have been 2 or 3 different config's for the PCV's, one non heated, and one electrically heated, and one coolant-heated. I posted about the PCv re-route I did on a buddy's Ford F-150 5.4 crew cab, likely about what Ultrashotone has. There was some kind of extra hose/vacuum nipple for his PCv system, I posted pics in the Index of it, check it out, Ultra. Point being- with Ford's they do things differently for different markets/regions/climates, the systems are configured different depending. IT could even be different ECU programming...
Anyhow, Ultrashotone, you did the common-sense thing, I'm glad for it!
Tracy G