Recently whilst stationary at traffic lights etc, the car has been revving up to about 1200rpm with no movement of the throttle, it only does it for a couple of seconds. Also whilst slowing down in gear on overrun the car is noticeably juddering.

My thoughts are either the water temp sensor or the lambda. Lambda is a year old and a Bosch one. I will get around to testing the water temp sensor soon but wanted your thoughts first.

Thanks
Jack