This sounds more like weak or worn springs...I am assuming they are original?

The symptoms you describe are caused by a suspension that feels as if it's "floating" rather than "tracking"

Generally MB springs don't call themselves to attention unless they are extremely old. So check struts as well...

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2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car