I have a 2007 Audi A3 S Line, and recently, I did a transmission fluid change. The same day I changed it, the car was driving fine.

The following day, suddenly, the car lost power, RPMs dropped, as it hit speeds of 75+ mph and the PRNDS on the dashboard began to flash. Turned off the car, and turned it back on and it worked fine.

For the next few days, the car was okay, until this Thursday when the car did the exact same thing.

It doesn't seem to be doing it at specific speeds, but rather randomly. Is the car going into limp mode? What could it possibly be? Thank you