Finally after months and months of trying different approaches to cure my Lexus 460s hesitations and sudden lack of power (limp mode style) have found the reasons why (in my case ) a collapsed tension pulley.. the cars knock sensor was picking up the intermittent vibrations my broken pulley was making and thus regarding the timing.. end result engine sounds and feels smoother and feels like all the 380 bhp are alive and kicking like they should be.. very happy with Lexus of Bolton UK for eventually finding the culprit..