radioactive

Mine is acting up lately on a 2000 Superduty 5.4 and I need to figure out why. I have read about the displays disappearing, but mine is bright and fine in that respect.
The miles to empty had been highly erratic, but lately it is stuck on zero and the mpg is a constant 11.4. (actual is 14-16) as far as I can tell the compass and temp still work ok.
What controls the info fed into the display? Where is it located and does anyone have a fix for it other than a new sensor or whatever it is that is fried?

Thanks