check rear shock system
Push down on the rear of the car and listen for the shocks. If it is bouncing to much that is a giving that its the shocks. Also make sure your tires are balanced.
Or you can take it to a pepboys and get a free inspection
15 year old car, mist likely you need new shocks
Yes, if it is bouncing, no need to perform the test, If you have over 60K, just replace them.
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