Had the same problem after changing plugs and cleaning the inlet manifold but mine was idling @ 1500, tried giving it a blast down the road then disconnected the battery for 5 mins, still no good, pulled off the grey plug and idle settled to normal so new it was something to do with the TPS. It was going into Lexus for a check the next day so left it for them to sort, by the time i drove there it was fine, they checked it and all was back to normal. Pretty sure ecu has self learning mode, just seemed to take longer than i thought, maybe i have a thick car