How in th eworld do people get 19 to 21 mpg out of these engines? On a good day I can't get 13. Truck vibrate and jerks like crazy when it shifts into overdrive any help would be greatly. Ford techs have been no help at all they say its suppose to run like this. I can't believe a 25000 truck is suppose to run like this 2005 f350 crew cab king ranch. Sweet truck but runs like heck thanks all help appreciated

Find a GOOD diesel tech that actually knows what is going on. The 6.0L diesels have had a lot of problems, Turbos, injectors and wiring issues all could cause your problems. Have a friend that has all of those issues, but he still at 140000 miles gets 19+ MPG on the highway.

There may be an idea or two in the following link that will help:

https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-8.html#post1415281

Having worked on a number of 7.3L PSDs and F-150s, I strongly recommend dropping and cleaning the pan (gasket is reuseable), changing the transmission filter, draining the torque converter, and refilling with either Mobil 1 Synthetic ATF or Amsoil Universal Synthetic ATF. Afterwards, you will be amazed how much better these trucks shift and perform. If you use full-synthetic diesel engine oil, synthetic ATF, and Mobil 1 differential gear lube, gas mileage should increase at least 10%.