Why 1998 VW Golf Driving normally engine cuts out and then starts up or not Sometimes after being stopped for a while it starts and cuts out within 1 second immobilizer removed but no fix?

Try Connector at back of ignition switch (key switch). Happened on mine, drove me mad for ages, checked everything then found that connector loose.

From original questio. It turned out to be a faulty relay under the dashboard. I had heard it clicking rapidly but thought that was the result of the problem and not the problem. A copper strip had broken and was making and breaking depending on the temperature or vibration or load. Cost 650€ for the VW dealer to find and 11€ for the relay!