Mechanic recommendations near Littleton?/Getting awful MPG

I have a 2013 6cyl trd off-road access cab, getting only 13-14 MPG, I have slightly larger tires, could that cause this?
What are others with the same year getting?
It is time for an oil change so I’m looking to get a tune up, anything specific my year and model I should have them check out/replace?
I live 20 minutes south of Denver, does anyone have any recommendations on mechanics in the area that I could go to for these things?
Thanks for helping if you can !!

 

how many miles on the truck? When's the last time you changed out your spark plugs? That and clean air filter should net you back to around 16-17 mpg which I think is avg.

Also dump half a can of SeaFoam cleaner in the oil about 100 miles before the next change. or put clean oil in, seafoam 100 miles, then change oil again. Dump the other half in your gas tank.

 

If you put it in neutral does it immediately slow down or does it coast properly?
If it slows more than you think it should, check your rear drums. I think they have a tendency to 'self adjust" to the point of dragging.

 

What size tires? Are they 10ply?


How long have you had this truck? How many miles are on it?

The oxygen sensors do “wear”, replace all of them with OEM quality replacements; Bosch, Denso, etc.