I've replaced both filters with MB filters. The fuel lines appear to be in good condition, but a pin hole would not be visible. Because the fuel lines on the banjo fittings are so dark, I cannot see if there is any air, just the occassional hiccup at idle when first starting it. This vehicle only has 94K miles. I still want to check chain stretch and injection timing. Currently I'm working on a design for a diesel timing light. That would make the injection timing much easier. We'll see! Thanks for the info, but I think the problem might be air getting into the fuel lines when it has sat over night. What ideas might anyone have to discount this theory? All ideas are welcome.