Rough riding air suspension

[mustangmad]

My 04 Expedition EB is riding extremely rough, crashing and banging over bumps. It's a 2wd, 5.4 with the 4 wheel auto adjust suspension. Pump works fine, truck sits level. It just rides really poorly. Mileage is 57k.

My truck has Bilstein air shocks. Do these units wear like a regular shock allowing the ride to deteriorate? If so, is there a rebuild service or other solution? Replacements are pretty pricey at just under $200(!) each! Yike!

I appreciate any suggestions.

Thanks