Car revving and vibrating while idling

[PrOxIMPURE]

Hi guys,
My 2001 golf GL has been revving up and down while idling at traffic lights. Sometimes when the revs aren't going up or down the car vibrates too. To stop the revs from going up and down I manually rev it up then it idles normally after until the next set of lights.
Has anyone had these problems before or any clues on what is wrong?
Could it be my air intake or air flow sensor?

Thanks

[heysie]

check over you engine bay and make sure that all your plugs are all in correctly.
i had a problem a couple months ago where my car wouldnt idle and stall when stationary,
all it was, was the air intake temp sensory wasnt plugged in properly.

[JustCruisn]

The up and down is referred to as idle hunting .
Could be sensor or vac leak is common also.

[aaron001au]

i had a similar prob on my 01 1.6 mk4 , turned out to be a small vac line had come off the pipe between the air box and intake , its worth just checking over every thing , or better yet , buy some carb cleaner and spray it on your vac lines if the revs drop then you got a leak in the area you sprayed