We are on our first trip in our new to us 1988 Escaper. We did maine to North Carolina and will be heading to florida as well. We expected better MPG on the highway. We were only getting around10MPG and it seemed to get worse when we hit the mountains. Wondered what other people are getting. I have a theory about what is wrong that I would like confirmed or dis confirmed. The truck seems to be running cold and from what I have read in the owners manual not letting the tranny shift into over drive. Could that be the problem? Is our thermostat stuck open or something? Any help would be great.