my vauxhall vectra sounds like it is going to cut out?

It would help if you told us what engine it is.

If it is petrol, this is usually caused by a dirty throttle body and/or idle air control valve, depending on which model engine it is.
The best remedy is to remove the throttle body, remove the idle air control valve and clean both with a carburettor cleaner spray and a toothbrush. Make sure the small breather hole low down on the throttle body is clear.
Refit using a new gasket (about 50p. from the Vauxhall dealer spares dept).

fred
September 2010