Engine Cuts out.

I have a 1988 Polo. It will not idle properly, this is most annoying whenever im driving and i try to change gear as the engine cuts out. My firend suggeted I adjusted the thing that regulates how much gas goes into the engine when idle, however i dont know how to do this. any help would be appreciated. i knwo this is located under the air filter but i cannot remove the air filter. If anyone could tell me where i could find a manual for the car it would be appreciated.

hassle..