2004 Ford F-250 F-250 6.0 diesel

Sounds like restricted Fuel filter

One of the biggest problems I found with Ford, is a bad connection on the battery cables, that will cause the computer to malfunction, check all your cable ends make sure they are tight, if there is corrosion visible you have to remove the cables from the battery, and cleaned them thoroughly, be aware that the battery post, and the ends, create a black hard corrosion, that can only be removed with the knife, or a file. It you suspect water in the fuel system, which is very common if you don't keep your tank full in the winter, diesel collects the moisture out of the air, remove your fuel filter, and dump it into a clean glass jar, then let it sit for a while, and check it for contamination, I can probably get your vacuum diagram, if you still need it, but remember a diesel engine does not make vacuum, but it does have a vacuum pump, maybe you'd better check it. If you could tell me more like, does it run better when it's hot? Is it hard to start? Is the engine light on? And things like that, you will help me, and I help you.