Continued Mileage issues/no help from Dealer

[fire8033]

I just picked my truck up from the dealer only to find out that they could not find anything wrong with the truck and they could not explain why the truck would be getting 12. 5 mpg unloaded. They said the computer was showing no problems and after conducting a fuel pressure check they found no problems. So I asked what the next step was and they said "Humm, I don't know".



This truck is bone stock and when I bought it 2 months ago I was getting 16mpg and above. Has anyone had a problem like this and does anyone have any suggestions??? It does not appear that the dealer will be any help.

 

[wcjp]

Any gauges? Curious if this is a boost leak. If no gauges it's not difficult to build a plug with air fitting and pressurize the system. When I tested my 96' I stayed at about 15psi. What's the age of the fuel/air filter/fluids? Are brakes dragging?