2002 Ford F-250 Super Duty 4dr Crew Cab Lariat 2WD SB (5.4L 8cyl 6M)
Now mind you I've done just about everything to this beast. KN cold air intake, Edge Performance chip w/on dash module, Weston Nerf bars, etc. now the issues I have is if the engine gets below 65 degrees it won't start except a whole lot of cranking. And then if it is way too cold like below zero it kills the batteries. I've replaced no less than 4 batteries ($90 a pop), 3 alternators ($550 a pop), a refit of the diesel/coolant system ($1800). Right now this thing has turned into a money pit, as i speak it sits dead again on my driveway, and yes it is plugged in, it's always plugged in
I can tow anything, and I mean ANYTHING when it runs
Sucks you've had so many problems but I can tell you that first off you need to get rid of the KN. They are known to dust the motors on the 7.3s It'll ruin a motor faster than you can believe. Spend the money and get an A&E or do your own 6657 mod. Also ditch the Edge and get a TS 6-position chip customed programmed by someone like DP Tuner, Tony Wildman (I have this one) or any number of other custom tuners. If you can't get it started at cold temps, have you checked your glow plugs? Cheap and easy fix compared to what you've spent thus far. I can start mine at 10 below without plugging it in all day long. Now I let the plugs warm it up for about 30s or so but it's been incredibly reliable for me.
Also check your IPR/ICP to ensure you're getting the right oil pressure. You can disconnect the ICP and see if it starts up. If so you know the ICP is bad.
As for your alternators, I don't know what ones you're buying but I got mine for $200 at Advance. I can't imagine $550 a piece, someone is taking you to the cleaners (please tell me you're not having someone install it for you. It's only 3 bolts to change.) Speaking of which I'm only on the 2nd alternator in 12 years so something else is a miss in your system if you're truly blowing alternators.
Again, hate you've had all these problems but hopefully this might help even if your post is 5 years old. :)