Vauxhall Vectra engine cutting out when slowing down

Hi. I was just wondering if anyone can identify with a problem I'm having with my car. It's a 1999 vauxhall vectra 1.8 16v, and the problem seems to be that the battery light and engine light come on and the engine cuts out when the car is slowing down or coming to a stop. This happens all of the time recently and am beginning to worry that it could be a major problem. The car is fine going at speed and when you don't have to slow, but in a town or traffic lights, roundabouts, etc... when you need to change gear and slow down the engine cuts out and car stops.
I have checked the oil levels...all ok
The rev counter when car first starts is just below the "1",
The car starts ok, runs ok, but just keeps cutting out all the time.
Any ideas ???
Someone mentioned that it may be the timimg belt/chain, but they weren't sure.
Many thanks.
Nicki