I had an issue with my '99 DI and thought I pass this on. At first I had fuel pressure of 28lbs key on engine off. I replaced the fuel pump (E3270). I also pulled the fuel rail and swapped out the fpr and installed used bosch 0280155746 yellow injectors (assuming one or the other could be failing after all these years. I pulled injectors from 2 late 860(?) models. To get a total of 8 I pulled from a non-turbo and turbo as the p/n is the same. There was a rubber dust ring that I removed before install. I'll be the first to say that I anticipate better performance when I do something like this. It could be sit-of-the-pants but the truck does seem to idle and accelerate better with these bosch injectors. That could be for any of the replaced though. I filled the tank and zeroed the trip meter. We'll see if there is any improvement in mileage.