I have a Renault Scenic atomatic 2005. It starts ok but when I take my foot off the throttle it cuts out, dosnt idle at all. I have managed to drive it with keeping my left foot on the brake and keeping the revs up with my right foot, but when its idling like this it is very slugish and lumpy. I have had it in the dealers garage and they hooked it to their computer and say its all fine.What shall I be checking, the sensor was replaced by renault in May