ckusy
Some things to check:
-Do you have a fuel pressure gauge? Could be a failed (or failing) lift pump or fuel delivery issue. If not, you may be able to disconnect the fuel line to the filter and check for fuel flow through the line. Just turn on your ignition without starting the truck. Your lift pump will run for a few seconds. You'll need to have a container to catch the fuel and a helper to turn on/off the ignition. Won't give you a pressure indication but will tell you if the lift pump is dead (not pumping). If it is blocked, maybe this will clear the blockage. Pay attention to the pumped fuel (if and) for contaminates.
-Check for dirty fuel filter. Could be a bad batch of fuel. It happens sometimes more often with stations that DON'T move a lot of diesel (like a neighborhood GAS station).
-Any Diagnostic Trouble Codes? If you don't have access to a DTC reader, turn your ignition on-then-off two times quickly and turn it on the third time. Any codes will show up on the odometer. Take pen and paper or a voice recorder (iPhone?) to jot them down. DTC information is available at the top of the thread in a sticky note.
You don't have any truck information in your post. Have you bombed your truck (heavily)? That will give us some usage information to help you as well.
Post what you find!
BF