That is a good explination of the torque converter dave.
Also search "torque converter" on YouTube. There are some very good videos on there.
For the mileage where do you fill up? I got a bad batch of gas this last time I went to HEB and the truck is barely making it down the roadright now. I usually run shell but I figured it would be worth saving 5 cents/gal because HEB usually has pretty good stuff. You would be suprised at how sensitive these trucks can be to fuel quality. You can try raising or lowering your most used gear (usually 4th). I have found that lowering the 4th gear can somtimes get better mileage but lowering the torque converter lock/unlock point to the extreme (-10 mph) can kill mileage because you have to give more throttle when it locks. The main thing to weigh is rpm vs load. Having high rpms are not the best for mileage (*past about 2100) but having high engine load (ex. result of making the truck shift ASAP) requires more throttle and more gas.
Here is a thread I started a while back based on compiled datalogs.
http://forum.gopowerhungry.com/conve...t-mileage.html
Also some tips that me and Jack have fount to be usefull for city driving that when you accelerate, go a little aggressive until you get up to speed. Then pull back on the pedal. I even installed a vacuum guage on my truck and so when I'm cruising I can balance speed with manifold vacuum (more vacuum means less throttle which means better mileage). I'd say that by adding that I can get at least 1 or 2 mpg by adjusting my driving.