Hi we have the same problem have been told its the hego sensor but others have said the ICV so if you solve this before us please let us know what it was think we are going to get garage to put it on machine to see if it picks up the problem its driving us mad!!
Take the idle air control valve off, spray with brake cleaner leave 10 minute, pour it out fill it with wd 40 leave for 15 minutes pour refit good as new.
Id have to agree with the above posts, sounds like an idle control valve problem, but would normally idle a bit rough if it was going. Does it idle high, or fluctuate??
Had the car plugged in at the garage...the machine didn't show up any faults at all,answering the above post the car does fluctuate a wee bit so we have ordered a new ICV and hope it is that have already tried cleaning it so I think its going to be a case of trying to rule everything out one by one..will keep u posted in case this situation helps anyone else.