Front Suspension problems of the 1998 Lexus LS400

Automatic traction control light comes on, there is a beeping sound, and vehicle swerves like it is going into a curve, usually to left. Problem will occur randomly over 40 mph, weather conditions do not play a factor in defect. Consumer states when problem occurs, the accelerator, brakes, and steering are actuated without any input from the driver and problem is not weather related, dealer has kept vehicle long periods of time, one instance for almost 1 month, always comes back and can not figure out the problem, consumer feels the problem is related to computer or sensor defect.