So, now that I know I have a 4 speed electronically controlled transmission versus a 3 speed hydraulically controlled transmission, I am having to learn a bit more before further tinkering. I don't know a ton about automatic transmissions, but I am learning. This PDF is a great read on how torque converter lockup has evolved over the years.
http://www.motor.com/magazine/pdfs/062006_07.pdf
I've also learned that the transmission code is: 4T40-E
Here is the
wiki page on it. A quick google search leads me to believe it has a 3.63 differential ratio, and along with its .68 4th gear ratio, gives a pretty darn tall geared trans (which I already knew due to low cruising rpms).