Vauxhall Vectra stalling

Generally the car runs fine, but every so often when slowing down, for example at junctions etc, the engine management light comes on and it stalls, it starts again every time and will usually continue to stall about half a dozen times then seems fine again, there is no pattern to when this happens. Can anyone shed any light that I may be able to do myself or at least so I dont get ripped off at the local garage.