I was driving around today, slightly over the speed limit, and drove over a bump. The car bottomed out 3 times, scraping either the frame or front clip/ air dam. The car is rather low mileage. I was wondering if just letting the car sit for 18 years has weakend the springs/shocks. Whats a decent shock or spring company to go with?

 

Sounds like your springs are shot. Sitting still will not kill springs but that doesn't mean yours aren't worn out. Chances are your shocks are shot as well. Try a few searches on which ones to go with. You will find all kinds of info and pics to help make a good decision that best fits your driving style.

 

bouncing is caused by worn worn shocks/struts.

sagging, "soft" ride, body lean, etc are caused by worn springs...

 

Time alone can kill springs. They are the only thing that holds your car off the suspension. Even just sitting they start to sag over time. Unless your shocks are all rusted up, inside or outside, they should still be alright because they only wear with usage.

 

Springs are probably fine. The shocks and struts need to be replaced.