RepairPal Certified shops can diagnose and repair your 2000 Mercedes-Benz S430. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.
A friend had same problem. It seems like your airmatic suspension is going bad. It's a common problem with these cars than the S500s. May be the suspension air compressor/pump-take to shop for diagnosis(also check REPAIR PAL's answered questions)