2017 T-680 Cummings 10speed auto

Have problem with my mpg being low 5mph-6mpg flatbed loaded or empty. Normal driving 68-70mph. Def delete, change a lot of sensors and filters, valve adjustment, re program. Mechanics said TURBO is carbonize and that my be the problem. Any advice from some one that has experience something similar?

 

Don’t understand. My truck 10 speed automatic

 

Truck with dry van heavy loads would give me minimum 7mpg then came to flatbed and better mpg but lately it’s been horrible only fuel at pilot and Loves

 

Yeah mistype and don’t know how to edit the title only

 

Thank you