Most likely it's your bushings, they are rubber pieces in the control arms designed to help braking, handling, and that soft Lexus ride.
A dealer repalcement will run quite a bit of money since they don't sell the bushings separetly. The plus to buying new ones is that you would get new control arms if one of yours is damaged by chance - which seems rare unless you've been in an accident. The down side being cost.
The other recently common fix is new poly-graphite bushings made by Daizen. They will help with the things above, but are slightly stiffer than the factory OEM rubber bushings. It is though, much better than riding on worn out/disentigrated bushings. These will need to be greased eventually but then, so does everything else under the frame.
Another possibility may be improperly installed springs/struts.
Last edited by Lvangundy; 05-03-04 at 08:52 PM.