milage drop

[notron46]

I have a 05,3500,4x4,6spd,slr,373gears,stock. Recently my milage dropped from 22/23 hwy, to 18/19. The truck runs great, and I live in central Fla. Any ideas what went wrong?

 

[SShafranko]

How many miles on the truck? Are going by the overhead or hand calculated? I'm not sure about Florida but in New Jersey i think we get the winter diesel mix and my milege drops every winter.