02 7.3 will not start but cranks over all day

[heavyr]

I have a 02 7.3 powerstroke it would sometimes not start back after shutting it off now It won't start at all it started just quitting while driven down the road for prob 5 seconds or so then it would pick back up an run. I just changed the crank shaft sensor an just about 8 months ago I changed the glow plug relay. I have a dP tuner on it also. If anyone has any tips for me I would sure ap very much thanks