Ford 7.3L Power Stroke (1999-2003) :: Truck Dies When It Comes To Stop

I know there are a few threads floating around regarding truck dieing, but mine is slightly different than the others, maybe its the same culprit, maybe not, but i thought i would start a new thread just in case.

First, I commute about 50 miles to work everyday, truck gets plenty of interstate highway run time, smooth as silk. About a month and half ago when i almost got to work I slowed to stop at a red light. As I came to a stop the truck "stumbled". Acted like it wanted to die but caught itself and kept going. I said whooaaaa girl, what this? Ive had this truck for almost 10 yrs now and never anything like this. About a week or so later, same commute, same red light, cept this time it dies. Starts right back up no problem. Just acted like someone turned the key off.

Then a week or so after that, while driving home this time, as I pulled up at the house to check the mail at the mailbox, when i came to a stop it died. Cranked right back up. Before I could put in drive, it died again. Cranked right back up and i drove on into the driveway. Then a few days later, while checking the mail again, it died again. Cranked up immediately and parked.

Today, while driving home, after i had gotten back to town, but before i got home i made a stop at bank drive thru, when i came to a stop, it died. While cranking it wanted to start and kind of stumbled on itself and died. Then it cranked right up and i came on home no problem.

So far it only occurs after approx 45min to 1 hr of operating time so the engine and everything else are at temp and far from cold. After reading thru some of the other threads of similar but different conditions (cold start dieing, dieing while under power, etc) Im getting flooded with ideas of what could cause it, but not settled on any.

1.Could be failing ICP? (original, has never been changed, 317k+).

2.Could be plugged fuel filters? (been a while since changing, approx 30k+)

3.Could related to one of my own earlier threads regarding possible failing alternator (when rpms drop can volts drop enough to kill engine?)

4.Could be loose ignition switch? (about 2 yrs ago i had to swap the blinker switch, to get to it had to remove the ignition. Upon re-installation the switch never did get tight as before and was loose. Been loose ever since. To the point that with key out of ignition and door ajar i will get the door chime as if the key was in ignition. I can bump the ignition, and chime goes away. Been this way for two years and no apparent problems. Until now maybe?)

I was thinking ICP after a few of the other threads, but after tonight Im leaning towards the ignition switch. I guess i can try to wiggle the switch after cranking tomorrow and see what that does for a trouble shooting effort. Is there a way to trouble shoot the ICP to see if its failing or not? Isn't that a fairly costly sensor? Would hate to buy one and not be the cause, but after 317k i may need to buy before too long anyway.