1985 Volkswagen Golf Engine cuts out

I bought the car and the owner said it had fuel distribution problems. I pumped the stale gas out by jumping the relay socket. I put fresh gas in. There is pressure in the system and the cold start injector works and the car fires and runs on the fuel supplied by the cold start injector. However once this fuel is burned off the car quits. It will then start again in the manner described but will keep quitting. Where should I look - at the electric system ( with emphasis on the coil and Knock sensor) or the fuel delivery system (with emphasis on the pressure balancing valve)? The OXS light is on on the dash.