I'm having this weird problem, after driving for about an hour, when downshifting (Automatic) to 2nd gear from third, sometimes my car almost stutters and stumbles. Does anyone have any experience know the reason why this is happening? It feels as if the car struggles when trying to shift from second or into second from third. I'm not sure the steps I should even take. I want to get it looked at but that would cost upwards of 700$ not even including repairs.

2015 A6 45 TDI Diesel