1.There should be no detectable play in any part of your suspension system. Finding this usually indicates a problem.
Press downward with your body weight on one corner of the vehicle. If it bounces more than once, the shock or strut is probably worn and needs replacement soon.
2.If your car is equipped with an Automatic Leveling System and your car seems to sit unevenly (i.e. the rear of the car sags), the usual cause is an air leak. Air leaks are usually caused by degradation of the rubber portions of the air shocks. Air lines and fittings can also develop leaks, causing the car the sag. In some cases, the problem could be the air compressor itself, or its sensors and wiring.
3.Most cars with factory air suspensions can be converted to a regular coil-spring type of suspension. While this option may be pricey up front, and the ride might not be as good as a perfectly-functioning air suspension setup, the savings in costly repairs can really add up.
4.On cars without rack and pinion steering, the suspension should be greased every time your vehicle has the tires changed or rotated, or every 10,000–15,000 miles (16,000–24,000 km).