Similar thing happened to my '90 300se except it drifted right under braking. I replaced the front shocks and bushes and it was ok after that. The previous shocks seemed ok but I guess the shock on the right had a little more wear than the left one. You can't really tell the conditions of the shocks just by looking at them. Hope this helps.

Kevin
'70 280sl 5spd
'90 300se
'98 E320