poor

Hey guys, new to powerstroke.org and really looking for some help. My truck has been getting worse and worse fuel mileage recently. I'm down to 9.7 mpg last time I filled up, and its looking even worse for this tank. Before I bought my current truck, I had an early 99 that was all stock except...

Well I finally decided to join this forum for help. First my 03 7.3 f350 dually has been getting poor poor mileage since we can remember (like 9-10 mpg) The only thing we have gotten for it was a k&n drop in. Other than that it is bone stock. I know its a giant truck with a gint engine but what...