Did you put significantly larger tires with the lift? If so, that could affect your in-town mileage since you would have effectively changed the gearing to favor highway cruise speeds. When I put 31X10.50's on my '88 Trooper it hurt the in-town mileage, but just a little.

There's quite a few "big meat" tire folk here, so hopefully they'll chime in with actual VX experience.