I have an 03 F250 6.0L diesel 4x4 and am only getting 16 MPG. I am looking for idea to increase the MPG.
In reading on here it talks about checking the chip that came in the truck. Does anyone know how to do this?

Switch to full-synthetics lubricants in engine, transmission, and differential. Together, this should increase gas mileage by 8 to 10%. My advice is to stick with the chip that came in the truck. Changing chips invites the "Law of Unintended Consequences."

What they are talking about is a performance chip. And what it does is change the profile from stock to modifyed. Many talk about increases in power and gas milage. To give you some idea here is a website.

Ref:

Performance Chips 4You - Truck Performance Chips