1990 Cadillac Deville AIR SUSPENSION ON 90 CADI Deville

Suspension problem
1990 Cadillac Deville V8 Front Wheel Drive Automatic 170k miles

I have an air ride suspension on my 1990 cadillac deville. Im aware of the leveling arm underneath behind the right wheel, which controls the lower/lifting of the vehicle. My question is that Im trying to figure out what part is responsible for the air ride because everytime I try to raise it up, it will not hold its lift and it will eventually sag back down. Im guessing its the struts but Im not a mechanic- if anyone knows what part I need to replace to fix my air ride situation, I would appreciate it. Also what part(s), brands and where would you recommend purchasing.