zafira cutting out and orange lightcomes on ?

my father has a 04 zafira and it is a good car except one fault an orange engine light comes on the dash and makes the car cut out when slowing down at juntions etc
we have changed lambda sensors ignition coil done full service new exhaust and yet the problem still continues dose any one know what may be causin this we need a cheep fix cause as with most folk cash is tight at moment
thanks for reading