7.3 starts then dies

[Rottweiler482]

I have a 91 f250 w/ 7.3L diesel, when i start it in the mornings or when i leave it for about 4 hrs or longer it will start right up then about 10-20 seconds later it will stall, then after cranking it for about 10 - 20 seconds it wil start right up and run good untill i leave it off for about 4 hrs or so.

Any suggestions on what could be making this happen.
Could it be a bad fuel filter, air in the lines or maybe even bad glow plugs??