I have a 95 f-150 with the 300 I6, manual 5, and 4wd with about 170k on it. On rare occasions during the summer it would randomly die as I was driving down the road after about 30 to 45 min. Let it sit for 10 to 15 min and it would start and run fine. about 2 months ago I ended up putting a fuel pump in it cause it quit. So hey I thought I had it fixed, but no. Now instead of quitting me randomly it just refuses to start. If I cycle the key a couple of times and give it a second it will cooperate. It has not ever failed to start but with winter here and my only other mode of transit a motorcycle this vehicle is kinda important to have operating regularly. I am thinking I am losing fuel pressure because of the way it will start, but I am not sure. No I don't have a fuel leak from a broken line during the pump change. It was the first thing that crossed my mind as well. With a new pump operating properly, about 2 sec on and the stop, my only other thought is a check valve or a regulator, not sure if this engine has either. Not real familiar with gas engines. Any and all help is appreciated.

 

First you should check the computer for codes, this thread will tell you how:
https://www.f150forum.com/f10/how-retrieve-trouble-codes-obdi-10907/
You should also do a fuel pressure test, both static and running.