Shocks only help ride and are not a means of support. The Air suspension is what keeps the car off the ground.
Do you believe that the Air suspension is original?
If it is the that would require replace of all the components which are , Air compressor, Solenoids and the 2 air springs. This is an easy task and should only take a few hours.
Here are some articles to teach you on how it works and how to pinpoint the problem,
click here
click here
click here
Good luck
__________________
Richard
1995 Lincoln Town Car Signature Series
Past
1992 Lincoln Town Car Cartier Designer Series
1992 Lincoln Town Car Executive Series
1990 Lincoln Town Car