91 400LS. Am still experiencing same Brake issue. After replacing right front Caliper and both front rotors, new pads, things worked fine for about 1000 miles. After that period, the front wheel with the new caliper would start heating up, i.e. braking. This would happen every now and then until all 4 wheels would start braking fairly hard (all 4 wheels showing same amount of heat) without Pedal input. Opening Bleed valve depressurized system and confirmed on Hoist. Also, letting the car sit for 10 - 20 minutes will free them up. Disabled the ABS, bled the system, same still. Rubber brake lines replaced years ago with the braided steel type. Am certain no cross contamination of bona fide brake fluid ever took place. Talked with the Lexus Tech to no avail. Anybody else found the cause/fix for this? Thank's all.