I had posted a few days ago about my 5.9 missing bad when I speed up. I ordered a pressure gauge and am waiting to recieve it. I will then check the pressure. While I am waiting for the gauge I have been researching and disscovered another possible problem. I have had the truck about 2 years and have changed the fuel filter but I have never changed the water seperator. I have only drained it. In reading the internet it sounds like I should have been changing the seperator also. Please advise me on this. If so I will change it before pulling a pressure check. Thanks