1987 300SL shake/wobble

My 1987 300SL suffers from shake or wobble that can be felt through the whole car ie. not just through the steering. The shake isn't present all the time and if the road surface is smooth its hardly noticeable at all. It seems to be initiated by driving over pot holes or rough surfaces whereafter the car 'oscillates' for a couple of cycles before settling down again.
Lots has been replaced at the front end - tie-rods, steering damper, idle arm bushings, shocks (all round Bilsteins) etc. and Mercedes have recently carried out a 4 wheel alignment. The engine mounts have also been cahnged most recently. The car handles better than it did but the wobble is still evident.
I see there are what look like dampers (2) next to the engine mounts connecting the engine to the chassis. These have not been replaced. Before spending any more time and effort on this problem can anyone give me some guidance on this problem and what the purpose of these dampers is and whether these could be significant.

Thanks