how can i fix vectra 97?

Remove and clean the throttle body and idle control valve using carb cleaner spray.
Make sure the small hole low down (where the narrower of the two breather hoses from the rocker cover connects to the throttle body) is clear.
Make sure the breather hoses are clear.
Use a new gasket when refitting the throttle body.
The idle control valve may need renewed, they are not too expensive for most models, but you dont say what engine you have.

asif
December 2010