check ride control light is on and rear end is low? on 1999 Lincoln Continental

the car bounces terrible HELP!

Asked by for the 1999 Lincoln Continental
poss air bag leak. they make an aftermarket shock kit for this that repl the air bag system
what do the air bags got to do with the rear suspension?
its called ride control and if the air bags will not hold air due to leaks in system, the car will bounce and have a floating motion.
Thank you is it an expensive job (parts and labor?)