Why is my Vauxhall Astra idling roughly?

My Vauxhall Astra has recently started to idle roughly, with the revs fluctuating between 500 and 1000. What could be causing this issue and how can I fix it?

This could be due to a faulty idle control valve. I recommend having it checked and potentially replaced by a qualified mechanic.

It could also be caused by a clogged air filter. I suggest replacing it if it hasn't been done recently.

Another possibility is a dirty or faulty mass air flow sensor. It's a good idea to clean it with MAF sensor cleaner or have it replaced.