Shortly after I bought my 1996 F-250 7.3L new it wouldn't start on a cool summer day. It turned over fine but would just smoke away and not fire. We were out camping and I had my wife turn it over while I gave it a very small whiff of ether and it fired right away and ran fine. After that, I used the block heater until I could get the truck to a dealer and it started fine.
The problem turned out to be the glow plug relay which I believe Ford either had a bad batch of or they redesigned it to correct the failing issue (can't remember for sure). In any case, it was replaced under warranty and I never had another issue with it. My FIL's 1995 model did the same thing. Point being is that the 7.3L is very dependent on glow plugs and if they are not working there is a good chance the truck will not fire even in relatively warm temps.
The fuel heater issue listed above is another possibility that I had forgotten about.
As much as that is higher mileage I doubt the motor is done and it is one of the issues listed in this thread. I have seen them with higher mileage than that.
OP, did you list the year of the truck? Sorry if I missed it.