Where's the Power? (electrical issue)

When you say, "reader" I trust you mean your volt meter or gauge, correct? I'd be suspect of the alternator (yes again...Ford had problems with em for a long time). Go to Advanced Auto or Napa or Auto Zone and they'll test it (the alternator and/or the battery) for you for FREE.
As far as the IAC...? I'm not sure what this has to do with this thread - the IAC, or Idle Air Controller, simply helps hold the engine's idle.
Same with the spark plugs and plug wires - this has nothing to do with the issue. They won't cause your engine to want to die when you roll up the windows. This is an electrical issue.
And a 4.6L Ford engine does not have distributor(s).

Like the above poster mentioned, if you put a load on the electrical system and the car power drops then chances are your alternator is going bad. Try some other loads (light with high beams, fog light, radio turned up, fan on) and see if the same thing happens. If not, maybe you have a short in the window wiring that is after the switch... but I would suspect that would blow a fuse so I would start with having the alternator checked.

defiantly check the alternator the lead and wires that connect to it too . i had a Bird that was having intermittent problems with it turning on and off replaced the alternator. as i was doing it noticed the wires that connect the alternator were all eaten up . i agree with GDawg but If you think its a short in the power windows id check the harness were it connects between the door. mine were broken in my 96 gt from the door shutting over the years but i never had a power problem just no window control. if thats the case i grabbed one off eBay for 35 . good luck