What's wrong with my Vauxhall Zafira 1.6V?

This is a 51 plate, petrol model. Last week after driving for about 1 hour on the motorway we stopped at the first set of lights and the car stalled. It started again, but everytime we stopped it stalled. The next day, when the car was first started it stalled again, but as it warmed up the stalling wasn't so bad, but now the car jolts when you're driving it. The exhaust emissions light has come on again. But this happens on and off. Please help!!