Poor fuel economy OS?

[superwagon]

My truck is a 2007 5.9 auto cclb 4wd Stock height. 285 tires AFE intake with free flow 4" exhaust and AD150. My rural avg has been 12-14mpg hand calculated with stock tune. It does not seem to improve with a little added timing and lowering rail preesure for the lower cruise areas? This has 70k miles and I replaced the injectors with stock II remans. I am wondering if a different OS might be a improvement but I am a little concerned about trying and don't understand what might be different anyway? Does anybody have a OS they use as a base for building tunes for customers that need a clean file to start from? My stock OS is a 11450201. Am I just expecting more than I should out of this truck as far as MPG? I figured stock tune would have been mid to high teens and be able to gain a few with tuning on top of that?
Thanks for any advise!
Doug

[Wheelz]

Most of my reading and experiences have pointed towards higher rail pressure improving mileage, instead of lowering it.

But I don't believe an OS change will make that large of a difference in mpgs. I'd say driving style would have a larger impact

[superwagon]

Our 03 suburban 2500 with the 8.1 big block averages 12-13 in the same driving. I really thought that the cummins would have been much better in the mpg department.

[2007 5.9]

My Big Single turbo truck averages 15-17MPG...so Id say that your tune may need tweaking.

[dodgeram5-92500]

Les tuned my truck and it was a rocket with dam good millage. Then I made minor tweaks to see if millage could go even higher, I'm getting almost 20 while towing my 18' flatbed trailer and I've seen as high as 24.5 if I take it easy. I'd give him a shout.