I have an 89 Golf CLI. a/t. I was checking on all my fluids yesterday and saw that the A/T fluid was low on the dipstick. Since I had stock of ATF from my previous car, I refilled it about half a liter. Actually the vibrations were less when I put it on D when the engine is cold. My problem is that its not shifting properly anymore, on low speeds up to 2krpm it shifts okay but on the open road, its having a hard time shifting, when it reaches 3K ++ then I shifts but engine is growling already.

Was it a mistake to refill the a/t?