I have a 1994 Chev half ton with 6.5 turbo diesel,

I have a 1994 Chev half ton with 6.5 turbo diesel, have problems starting, motor turns over, lots of fuel, fuel pump working, has a mind of its own, when it wants to start. Some times a few hours after trying to start it, & its starts,some times not. & in the past when it was running, sometimes it would just shut down, but would start back up, starting problem wouldnt make a difference if motor was hot or cold.