Explorer 4.6, p1507 code, rough cold idle, SES light

[68panther]

Got a 2002 Explorer with 4.6 V8. Since I bought the vehicle, it idles rough after starting and frequently dies. Once warmed up, (1-5 minutes) it runs generally well.
Service Engine Soon light also comes on intermittently (a few days at a time) and turns off just as often. I ran the codes and come up with P1507. Research on this confirms it is often related to IAC valve.
I inspected the IAC, expecting it to be dirty and yet it looks flawless; almost brand new (bought the car a year and a half ago and suspect it is roughly that old). Unplugging it while engine is running seems to have no effect on idle. Haynes manual is lacking in info on testing IAC.
I've searched for vacuum leaks, cracked hoses, etc. without luck. I'd hate to replace IAC if it's not the problem. More research indicates EVAP purge or EGR could be contributing factors.
If anybody could help me with this I'd be much obliged. Thanks

 

[Joe in NY]

If the IAC is spotless and no effect when you unplug it (there should be) that is a good indicator of bad IAC.

 

[68panther]

Replaced IAC and gasket and disconnected battery to allow it to pair with the computer...still no effect when it is unplugged while running. It may be receiving a bad signal? Two wires going to it: violet/white and white/blue. Violet wire has 12V running to it. White wire shows high at 30. Not sure what to make of this and it still idled rough at cold start