4l80 questions

[Billett]

Got my TCC wired up the other day hoping to improve the 14.5 mpg I calculated on my last trip. Filled up yesterday at an estimated 12.2mpg... now I try not to consider myself an mpg freak, but I could have done 12 with my 350/ granny gears. Anyway...This is a 2 question post:

1: what kind of rpms are you guys turning at highway speeds? I know I am running with 3.73 rear but 2400 at 70mph seems high compared to what I've read here. It calculates out about right with my 28" tires but I've read under 2000 from some on here...

2: how can I test that the TCC is even functioning? Or that I have one? 4l80 is from a 95 van, pcm is 2003 van. I heard that if I maintained throttle in 3rd or 4th and pressed the brakes enough to throw the relay then the TC should unlock and I would jump up a few hundred rpms. I tried that to no avail... Only other thought is that this pcm has not been tuned yet. Is that a function that can be turned on/off and might just be off at the moment?