Went on a long drive yesterday with the well cleaned original ICV and no idle problems at all. Phew.
What did cause a problem though was a large pothole 4 miles from home. A big bump and the engine just died. Pulled to the side of the road and to cut a long story short the car has been recovered to Williams Morgan who found the 5A dashboard and immobiliser fuse to have blown but not sure why. Really strange symptoms - no gauges or warning lights and nothing on the key or starter button but the headlights and indicators worked fine. We were travelling up a steep hill on a country road at the time and not safe to fault find beyond cursory checks. Its due an MOT in three weeks so taking advantage of garage time - hope it passes and will collect on Friday.