The fuel filter was replaced a few weeks ago.
Blacklung, you are talking way over my head. I just got the truck a few months ago and it's my first diesel so I don't know much about it. As far as I know it's all stock w/ the silencer ring taken out, BHAF, and a 4" turboback. Please bare with me while I try to answer your questions.
Lift pump, is that the fuel pump?
I don't have a fuel pressure gauge.
There is no check engine light on, so I didn't think there would be codes.
What is a VP44?
Sorry for my ignorance, this is new to me. I would like to learn it though! I was told it could be my injectors. For what it's worth I have just over 90k miles.