I am new to LS motors and electronic transmissions and have some small questions.
1. I put a 2800rpm stall in my truck. Do I say goodbye to good gas mileage?
I was driving the other day and thought "Theres no way this thing could get more than 12mpg - its over 2000rpm constantly!"

2. My truck has DBW with TAC. Do these "learn" sort of how the pcm learns? Can they be adjusted in a tune? It seems very inconsistent like sometimes if I make a minor adjustment with my foot at the pedal it will make a major adjustment at the throttle body. Also, sometimes it has idling issues. Could an IAC or TPS sensor be messing up?

3. Is there only one 4L80E tuning calibration for all years of 4L80E?

I realize these questions might be worthy of their own threads respectively but I figured they were probably easy questions for you guys and it better than flooding the forum with little threads.