I have a Zafira GSI and it randomly cuts up upon breaking to a stop. I.e I am breaking for traffic lights, when I stop it cuts out. I then go to turn engine back on and it turns but just does not start. Its really annoying. I can bump it if on a hill and it will start.

I went to a garage yesterday to check the battery and thats fine. I was told it could be air flow meter or possibly crankshaft sensor, but what do you think as I dont know what to buy to try first.

Anyone experience this problem?