I have a 2000 F-350 7.3. Here is my problem. The overhead display thet shows milage / outside temp / miles to empty etc. has went nuts. I will read that I am getting around 26.6 mpg all the time, which is not even near correct. Also the " miles to empty " hardly ever drops below 500 or better. I mean if I only have 1/4 tank it still shows better than 500 till empty. I do have a " GOLD " plug in super chip on the truck, but it has been there for about 7 years now. Anybody ever had ths problem? Please help. Thanks