Vauxhall vectra 16valve engine surging at idle up down continual?

Check the fuel injection air-intake. I had a similar problem on my Alfa when there was a leak in the pipe between the air-filter and the manifold. idle control switch on throttle body try taking off the idle control valve and giving it a good clean out with some choke and carb cleaner it comes in a spray can i had this problem with my vectra apparently it is a common fault with them once i cleaned the control valve all was ok