you can test your O2 sensors with a volt meter and a propane torch but if your SES light isn't on they are probably ok

 

So what is your air pressure, beside fine, how many miles on your truck and what were the readings from your 02?
When was the last time you decarboned the engine and how hard are you driving it?
my 99 D2, at 6000 feet gets 18.2 on the road as long as I stay under 70 MPG. What are you missing?

 

How many miles on your engine, what air pressure are you running, was was your engine decarboned, tuned with wires?
Something not right, my 99D2 gets 18.2 at 6000 feet on the highway as long as I stay under 70 MPH.