I just got a 1995 E320 less than a month ago from my Uncle. He had previously replaced the transmission and I haven't had any problem with it until now. It has an automatic transmission, when I accelerate slowly and it change from 1st to 2nd it jerks like I just hit a bumper. When it first occur, I thought I did hit a bump, but it occurred a couple more times and I have no idea why its doing it. Any one have any idea what may be the cause?

 

If it's that severe, it sounds like you have transmission damage to one of the clutches that is not engaging correctly. I would try, in order:

See if it does it in both S and W mode.
Sneaky ECU reset to see if it is the shifting algorithm.
Transmission fluid change to see if the fluid is bad.

After that, it sounds like there may be actual damage.