After checking with my General motors bulletins there is quite a few issues with your vehicle when it comes to transmissions. Is your engine light on? Have you had it checked for codes. Do you have any leaks?

No leaks, no engine light on, just response from the GM techs when I asked about a software upgrade for the transmission that after checking, it was the tcm/valve assembly going bad.

You wouldn't happen to have an insurance monitoring device plugged in to your diagnostic connector under the dash would you?

No, nothing out of the ordinary except that the transmission wants to downshift over a little anthill and the rpm's go to 3000 so the gas mileage is shot.

Acadias do have finicky transmissions but I think you are at the point where it should be scanned and checked out at a tranny shop. There are too many variables to really know unless it is opened up

Okay, thanks. I am going to drop it at the dealer's this afternoon and let them have a closer look. Hopefully the news will be good or at least bearable.

I am guessing your are out of warranty but possible drivetrain warranty. If you have been good about maintenance don't hesistate to call Gm customer service to see if they will help you out if you don't get anywhere at the dealer

GM is going to cover 2/3 of the cost of repairs as the vehicle went out of warranty in May of 2012. Bought new and never did like the transmission.

That is awesome