Have you been putting in straight ULSD for the past year? Alot of the seals for like the fuel filter, and i think the injectors were designed to expand from a reaction with the sulfur in the fuel, making a perfect seal......thats the problem with ULSD, not enough sulfer content to make the seals work perfectly.
If you have no codes i would suggest a fuel lubricant like K-100 or Powerservice.
Sorry for the late post...