1998 Lincoln Continental Right Rear Air Suspension

Hard to say exactly what part will fix it. It could be a bad air bag, check valve, leak in the supply line or a bad compresssor. Those vehicles are famous for being difficult to find the leaks in, and it can get quite expensive to be honest, (bags are a few hundred dollars apiece). I have converted many of them over to a coil spring rear suspension and not had any complaints about ride quality. Strutmasters makes a nice kit that includes instructions to keep the suspension warning light from coming on