Cold Start Iissues After Extended Sitting

[Diesel Max]

Strange problem going on here............... Seems when the truck sits overnight, it has to be cranked for a while to start. This only happens when the truck sits for an extended period of time. I can drive it to work and leave it sit for 8-9 hours and it starts with no problem but when it sits from about 6 PM at night until 6:30 AM the next day its hard to start. When first cranked, it will try to start and run for 3-4 seconds and then die....... almost like there is air in the fuel system. Then after I crank it for about 8-10 seconds if will finally start and run. Sometimes it will start fine after sitting overnight and other times it wont do this unless its sat for 2-3 days. No problem starting at all when it's warm or sat for around 8-9 hours. Glow Plugs seem to be fine, GPR seems to be acting normal and I just changed the fuel filter thinking maybe the old filter was dirty causing hard starting............ I can't find any fuel leaks anywhere as I thought maybe air might be getting in the system causing this.................. The truck runs great and mileage is still good as well................ Any ideas ???????

Thanks

 

['94IDITurbo7.3]

i would say air intrusion

 

[Diesel Max]

Would seem logical but can't seem to find any leaks.............