ls400boi

My 1990 LS came stock with the air suspension. About 2 years ago, I switched from air to coils. All was good until like 2 weeks ago. Currently, the car rides extremely stiff as if the car was still running air ride with too much air in the struts. It's kind of weird because I thought that when a coil strut goes bad, it rides too "floaty"? Do you guys think something else has gone wrong? Just looking for suggestions as I have searched and found nothing or no one with any similar problem. Thanks