I'm guessing your "more aggressive tires" are the cause. If they are larger in circumference they will throw your speedometer off which messes up your mileage calculations. Also tread patterns and added weight to the tire can have a bigger impact than you think because you are talking about 'rolling weight' which is the worst place to add weight.

 

You can get an fuel/air ratio guage at summit racing or jegs for $40 us , what size engine,i ve done brake jobs and or had 4x4 hubs dryin up that cost me gas milage.Have had small gas leaks that werent noticed till on highway,was the fuel filter changed?

 

ok well the mileage is back up but not all back
i have a 4.8 and the fuel filter is in the tank so i can't change it
my hubs are newish (1 year old) about 23k on them i would guess
my tire are the same size as the originals but more aggressive


thanks

 

final update


Thnaks for all the replys you guys gave me


The milage is all the way back up yo par when i first got the truck runs great no probs.

it took some time but it did go back up list of things i did


1 air, filter plugs (tune up) ect...

2 Seafoam oil, gas, vacume line,

3 and i think hte biggest factore becasue nothing realy happened until i did this is change gas and gas station after that my gas mileage shot up from that point and has stayed up



again thanks everyone for the replys.


Breaz