I was just about to post this in a new post, but since it's sort of applicable here...
I just got my stock '04 FX4 engine management program upgraded to the newest release. Initially, it was done to try and fix the spark-knock I was experiencing.
IT WORKED!! Also, my milage has gone from 15-16mpg, to 18-19mpg. I do drive my truck like a grandma, but I always have, and an increase is an increase.