I am not a pro, but in having my suspension done, If I understood my tech correctly, Bilstein does make 3 different shocks - std, HD, and sport. The sport is the same firmness as the HD, but a shorter travel shock for shorter springs.
Also, a number of people on this forum have discussed handling problems on 300Es (try a search on this), and I believe they concluded that changing the rear lower control (thrust, push-pull) links and bushings solved all their problems. I also recall someone saying they were meant to be exchanged around 80-100,000 miles, about the same time as the steering damper.
just my thoughts, I'm sure a number of people with more tech knowledge will respond on this as well.
2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)
Click to see 87 300E