My 2000 F-250 has started acting funny. I has started idling rough and louder(pre hpx) and it seems like it has a miss in it when its between 1300 and 1800 rpms(not when excellerating). It all started after I changed the oil(rot5-40syn) and filled up the tank. That day it also got really cold and when I excellerated it was very jumpy. My first thought was fuel gelling (fueled up at a different station) but I use the diesel kleen white during the winter. Then when the temp warmed up the truck ran fine. Then the symptoms came back. Since then I have had the truck scanned, no codes and the injectors where tested and all checked ok. The diesel tech wanted to check the fuel pressure at a differnet time. So instead of paying another $80+ to have it check I bought a new fuel pump on ebay for $140. Needless to say still running the same. I replaced the CPS about 12000 miles ago when I had a miss around the 1500rpm (didn't help). Also I've changed the oil and fuel filter and have went to my ussual watering hole and filled up with no change. It seems to have lost some power. Fuel mileage has dropped a little. It isn't smoking. I'm wondering if it's a sensor or something worse.