Help me with my 2.0CD Vectra PLEASE!!?

I have recently purchased this car and it is driving me mad...
1. The EMS warning light is on for 50% of all journeys.
2. The engine cuts out when I stop at lights or decelerate.
3. The engine has cut out twice while I was doing about 70mph on the motorway. The rev counter was bouncing around, even though the red lights were on in the dash. All power was lost, but then it started firdt time from the hard shoulder.

Can anyone please advise me????