Hi all, new to site, I recently purchased a 2005 dodge Cummings Isb 3500 duelly with 22000 miles beautiful truck just like new. Never had a diesel before, when I drove it home I inboard computer stated 14 to 15 mpg, let me add I was pulling a 32 foot 5th wheel. In the last few months my mileage has gone downhill, now empty I am getting@ 13 pulling 5th wheel @ 9 I have done all servicing. I thought I read something about. The dealer reflashing it ? What is that if my terminology is even correct. Sorry about the grammar I'm trying to do 2 things at once. Thanks for any input. I don't think I will ever buy another gas engine😃 Darrin