My 92 spent lots of time in the shop during warranty, and they replaced all kinds of things, upper control arms, drive shaft , steering damper, etc, etc. The best it ever was when a MB shop in Chicago balanced the wheels and then balanced them on the car with a strobe.
A while back I did engine, trans mounts, lower control arm bushings, steering damper, and sway bar links. I also went to Bridgestone Turanzas (road force balanced) and cranked up the pressures by three pounds. I do get an occasional vib at 40 or so but it diasappeares after a while. I did have the tires rebalanced, and the shop did not have the machine, and it seems to be back slightly. The car shipped with Pirelli, and they switched out the tires to Bridgestone, I have gone Bridgestone with both H&V ratings and was not happy. As they say you can balance a brick to spin but it will be square
As I stated in 95 the car was lowered with different springs and rates, I have never done shocks, but numerous alignments. I dont think your vib is the cronic issue with some early 140s, maybe warped rotors, bushings, maybe tires.