Citroen AX - Engine stalling

HI. I have a 1995 Citreon AX 950cc which has done around 52,000 miles. For some reason the engine occasionally cuts out when I'm in motion. Sometimes the car will start up again straight away and sometimes it takes up to 15 minutes before it restarts, once going again the engine runs fine. I have changed the air and fuel filter which seemed to rectify the problem for a couple of weeks but it has strarted occuring again. Please note that the car is a fuel injection model. Does anyone have any suggestions as to what the problem could be? Many Thanks all.