Sensitive steering.

[airmechanical]

Hello everyone,

I have a 2013 base GS350, with 150k miles, car runs excellent, and the steering work as it should, except for one thing, and I am wondering if it is characteristic of this model or if there is a problem that I am not able to find.  The issue:  If I turn the steering wheel abruptly from left to right and back very slightly while going down the road, from speeds anywhere from 25mph and up to 70mph, they car seem to rock quite a bit, like that of a boat on rough water.  I had a seasoned and trusted alignment mechanic looked at it a couple of times and could not find anything.  The car had an alignment not long ago, tires have good air pressure, front passenger tire slightly more worn on the inside edges (prior to replacement of worn upper control arm).  I replaced all struts/shocks with KYB (which is OEM), Lexus upper control arms due to worn ball joints, checked front and rear sway bar bushings, all good, yet the problem persist.  If anyone have had this issue and found a solution or found it to be definitively characteristic of this model, please let me know.  I appreciate any help you all can provide.

[Dean2]

Does this change when you put it in sport mode which firms up the suspension and steering?