AIS cost me $214.00 delivered. With the fender sleeve it will flow more air than most will need. (which I haven't done) No turbo whistle and I haven't noticed any turbo surge yet. No warranty issues.
In regards to 7.3 it is a box that goes between the injector harness and the valve cover plug which allows you to shut down one injector at a time. Used to isolate a bad injector.
Easy to check out GPs. Pull valve cover plugs. The two outside connections are for the GPs. Just ohm them to ground. Betcha got a couple that'll read zero.
Certainly sounds like a fuel issue. Either gelling or low pressure. Don't know where you are or how cold it is. Might try throwing in a gallon of Kerosene.
That is normal for a cold engine. The cold weather package will close the EBV until the oil temp gets up to normal.