You might want to check your self-leveling system. There are two ball (?) can't remember the correct name but my M-B mechanic said the problem is probably there. This check might be cheaper than replacing all the shocks.

Dick Diefenbach
'93 300TE 182,000
'85 280 SL (Euro) 60,000
'64 230SL (4 sp.Euro) 60,000Km, 3rd time around