high pitch sound coming from engine

hi, I've had my audi a4 for about 6 months now and it's idle has never been right, but has got worst in the last couple of weeks.
I've read on the internet several places about cleaning the MAF sensor which fixes it, but, I don't have the courage to take it out, clean it in alcohol and dry it for 24 hours (or whatever is required)
Anyway, I've ordered a new MAF sensor which is coming tomorrow.
It looks an easy swap. Is it standard socket set stuff or do I need any audi specific tools.
your advise is much appreciated.

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MAF sensor is easily replaced. 1 electronics connector, and four 10mm nuts (as I recall).

You will need to remove the top of the air box, and remove the pipe that goes into the MAF, but apart from that it should be a 10min job

One thing to bear in mind is that its not only the MAF that can cause idling problems...

Also check all air pipes to make sure there are no leaks, and if that's ok, then consider having the throttle body cleaned.

I was thinking of giving it a clean with isopropyl alcohol but thought, not worth the hassle so ordered one from a nearby trustworthy shop.

I picked it up the other day and had it in the boot waiting for a dry day, which came today. Thanks for the advice about the work needed.

You were right, only a 5 to 10 minute job. Problem is, is't still not right so it may be a case of checking all the hoses like you mentioned.

I assume the throttle body is at the other end of the air pipe to the MAF sensor. This looks a little more complicated than the MAF but I think I'll be able to do it. Thanks again for the info and I'll post a reply asap.

Word of warning though, if you attempt to do the throttle body yourself, is that when the throttle body is put back in, it NEVER goes in the same place, and the ECU needs to be calibrated bvia the VAG COM interface.