Hi All , Corsa 1.4 about 1998, rough ideling , gives good petrol figures , when driving down a steep hill it will give "hunting idle" , very lumpy and cut out. Orange light on. Start , will cut our again , start a few times and get going with orange light flashing , engine going well , then it just cuts out, like you turned off the ignition. Then start and it goes fine until it sees a hill again. While driving up and down under throttle its fine but dont lift your foot off the gass. Any ideas, have done the HT leads , plugs , idle /throttle sensor, and the one against the "firewall".