Yes, your struts are shot and you must buy the PSS9's today or your car will forever run poorly!
Seriously, have you been able to look at the strut and see if you have any oil coming out of the seals? If you are able to compress the rear end of the car with your hand an appreciable distance you are probably seeing the struts go. How many miles on them? My cars died well before the 88K when I bought her and what your describing is what mine sounded like.