either the 2.3 or 2.5 4 cylinder models. keep your tire size to no more than 32 inches and as skinny as you can. get either 3.73 or 4.10 depending on tire size. a light touch on the gas pedal. use the cruise control and keep speeds around 60-65 on the freeway. regular oil/filter changes along with air cleaner. and, as above, forget the turbo. do a body lift so there won't be any alignment issues. that lift will also preserve the original ride and handling for you. and the money you save over a suspension lift will buy you lots of gas for sure.
that should be a good start to a good gas mileage 4x4 dd. oh, Welcome to TRS!