Citroen C5 engin cuts out while driving

The engin cuts out while driving and wont restart.some times it will restsrt after 10 min and drive for a week and sometimes it will only go for a mile and stop again. It has had the injectors changed last august and it seemed to solve the problem although the engin was lumpy since and now the same problem is back again. It has had a full service recently. The warning beeb goes off a lot the temperature light goes on when the engin is cold another one for speed too high and then just a beeb and no read out. Help Please