If you know how to check the trans level, I would check it. Mine was shifting hard and found it was short about 1 quart of trans fluid. Once I filled it, it was fine.
I thought so till I did some research. I was getting annoyed with the hard shifting from park and I only have 27K on it. It had been doing this for a long time and thought it was normal until I decided to do some digging. That 1 quart of fluid changed it. It shifts into gears smoothly now...
There is a fill port on the driver side toward the rear of the transmission when you get underneath the vehicle. You have to have the transmission somewhat level, the trans fluid between a range of like 86-122 degrees and the engine. You can find some youtube videos about the ZF transmission...
Mine was shifting hard from Park to drive or reverse. I decided to check the transmission fluid level. It was about a quart low from the factory. After adding, the trans shifts smoothly now.