I just removed the EGR on my '86 300sdl and drove around the block. Immediately noticed hard shifts, was always smooth. Put EGR back and it's normal now. I did forget to plug the egr vacuum line but when I plugged it, it was smoother but still a bit hard. How is this caused? I know I didn't plug the line good maybe that is why. On my '92 300sd I removed EGR and I got smoother shifts.