I've lost like 3-5mpg in the last two weeks and my power seems to come and go. Part of the it pulls mormal and part of the time it won't hold speed with my trailer.I have never gotten less than 11mpg pulling up to 20k. This weekend I pulled a 8k load 600 miles and got around 8-9mpg : . I called the dealer and they said there was nothing they could do and that that milege sounded normal . This is probably the injectors going bad right.The filter was just changed so it's not that. I need help asap.