I was driving with 1/2 tank of gas then suddenly it went to empty and the light lit up. Stop for a while turned engine off/on and gas gauge went to full tank. What could be the problem? Any ideas? Thank you

 

My first thought would be the fuel pump/fuel filter. If I;m not mistaken the fuel filter is built directly into the fuel pump and perhaps the component that monitors the fuel level in the gas tank is starting to **** the bed on you..... thats my best guess. How many miles on your truck?