If the fluid/ filter change and adjustment dont bring it up to your satisfaction, start saving for a DTT, Suncoast, et al, transmission. Expect to spend $2500-4000, depending on how much power it needs to hold. But, one guy here gained 4 or 5 mpg with a Suncoast transmission over his stocker, the stocker was THAT sloppy. I think Mom's could gain 3-4.
Daniel