Originally Posted by snrusnak
I wouldn't expect much more than 15-17mpg out of that engine in the full size truck. I also wouldn't run the Jet chip, it won't do any good and will only screw up the A/F ratio. Also, check to make sure front and rear O2 sensors are the same part number, they are usually not and you can't swap them.
Thanks for the heads up about the O2 sensors. I've had this truck for several years now, and was getting 18-21 mpg consistently from it. I've dyno'd the jet chip as well as stock and performance tunes on the truck, the a/f is fine w/ the chip and although the gains are small and only in the higher rpms, they are there.