You have checked the fluid with it running and warmed up I assume. The
hiway milage depends on how you drive, the tires it has, if it is lifted
our not, the terrain you drive in, engine size and overall gearing of
truck too. (Lots of varibles here as you can see)

-----------------
www.thesnoman.com

My Ram transmission (47RE) does that too after it's parked for an extended
period of time. If I drive it every day there is no problem. If it's parked
for more than about 3 days I have to idle it in neutral for about 30 seconds
before putting it in drive. After doing that it works properly again. I was
told it's caused by the torque converter draining the fluid back into the
transmission while parked. Idling in neutral fills the converter again much
faster than in park. It's a minor inconvenience and not a big problem. It
isn't a sign of pending transmission failure. I don't think 16 mpg is
abnormal mileage for that vehicle.

I have a 2001 Dakota QuadCab, 2WD, 3.55 axle, 5 speed manual, LSD, 4.7 V-8,
about 24,000 miles on odometer. The trip computer, which I have verified as
being pretty accurate on several occasions, reported 20-21mpg at 70mph,
22-23mpg at 65mph along a 150+ mile stretch on a recent 850 mile trip in
late August. Conditions: Empty/no load, A/C on (except for about 100 miles),
driver only, negligible wind, Interstate highway, light traffic, outside
temp. around 90 degrees.

Average trip mileage was right around 22, driving most of the time between
65 and 70mph. I did draft a few semis, but only for about 100 of those
miles. I figured I spent about $100 total on gas.

I have averaged right at 17mpg over all 24,000 miles, mostly in-town with
some freeway driving.  Mileage really drops at 75mph: I get only 18-19mpg at
those speeds. I try to upshift at 2K or less unless I am having fun or
accelerating on a freeway ramp, etc. I think being a 2x4 and not 4x4 and
3.55 vs. 3.92 really helps the mileage. I don't think the manual tranny is
inherently more fuel efficient than the auto.

--Clay