Engine/Transmission (1998.5 - 2002) fuel miliage?

[duckcarvr]

I have only had this truck a month. So no long history here. My first tank was all around town driving and i got 14 mpg. my second tank i filled after only 146 miles so i could get a sample of what i would get on the hwy. of the 146 miles- 90 plus % was on the freeway. I only got 16 mpg. I seem to have good power. But I hear talk of 20 to 24 hwy and also talk of VP44's and of LP's. Do i have a problem?