1999 Grand Prix 3.8 Transmission Issue? 130K miles

Hi, at 65,000 miles my Grand Prix began doing this slight lurching thing when you applied a little gas. If you backed off the gas pedal or pressed harder on the pedal the lurching stopped.
After testing several things The Dealer said I needed a new transmission and after $3,600.00 I went to pick up my Grand Prix with its “new” transmission.
As I was driving down the road I couldn’t help but notice that it was STILL lurching as it was before. The mechanic said that he forgot to “re-boot” some electrical component that’s associated with the transmission that had to have the power removed from it for 24 hours so that it could “unlearn” the bad behavior that my old transmission had taught it. The next time I picked up the car the problem was gone.
Well, here I am approx 65,000 miles later and the same exact problem is returning. I’m pretty certain that the Dealer scammed me the first time, however, I’m not 100% certain of this and I want to avoid making the same mistake. First of all, is it possible that the Dealer didn’t scam me and second, what else could be causing this slight lurching thing when accelerating?
I’ve gone through 3 cans of injector cleaner and a new fuel filter, plus a transmission service with new filters and fluid. Also new plugs. No help.

Any suggestions from the gurus would be appreciated. (And rewarded)