Help bad fuel mileage

My mileage around town is 10 to 11 mpg. The truck is running perfect. I drive mellow and the mpg use to be 14 to 16. I took it to toyota and they checked the computer and everything was ok. The truck has 62k miles and is like new. Could winterized fuel be the culprit. Any ideas out there

 

You on a lift and 35s?

 

Nope stock tires and wheels

 

Well, good news, bad news. Burn the remaining fuel and refill with premium. Check your brakes to ensure nothing is dragging. Check vacuum lines and intske filter, just in case a rodent has stuffed your airbox with stuff.

 

Nothing to lose if you add a fuel stabilizer and cleaner to remove moisture in the tank. I use Seafoan, and it does a good job. Just make sure that you use the right kind of Seafoam (read the label). I use it on my chainsaws, lawn tractor, and so on- when storing them for the winter. Now, where I live at (Alaska) alcohol-based fuels aren't sold at the pumps.