G'day folks, I'm wondering what the final outcome was here? I have recently had similar problems with a customer's TK Barina, and long story short, it ended up being a failing Idle Speed Control Motor which finally seized.
Also, on a related issue, I also recently had an Astra in with similar problems, which turned out to be a failing fuel pump. Contrary to previous comments, it is possible (in fact quite common) for a fuel pump to die a slow painful death. It can take months of the car intermittently not starting or stopping for no apparent reason before the pump finally packs it in. Often, at the times when it won't start, if you slap the bottom of the fuel tank hard with your hand, you will find the jolt is enough to make the fuel pump start running - until you turn it off again. And these days, 9 times out of 10, I find that the owners of cars with failed fuel pumps (in fact, failure of any part of the fuel system) have been using either E10, or poor quality/contaminated fuel.
