You need a new idle control valve. Cleaning it is an temp solution and does not work on all cars. Try E-Bay. Type in idle control valve, look 4 LMF Vauxhall. @ present an ICV is £45.
Dealer is doing it 4 over £100. I did it this way and my vectra has been driving better than ever.. Good luck..
Jimmy Shergil
August 2005