Another thread

On a 60 mile run going 60mph - 75mph my car turned back 33mpg rather than the usual 36+mpg I normally get.
I've also noticed that at around 3k revs the turbo has started sounding a fair bit louder than normal and has developed a kind of whooshing noise.
Anyway, I suspect a vacuum leak and I was wondering if there's a way to test the idle values on the agu like you can on the 01+ engines.
I've tried measuring block 032 as suggested, but that doesn't turn back any results, I then read that the equivalent for an agu is groups 7, 8 and 9, but I couldn't find anywhere that tells me what to look out for when inspecting the values.
Can anyone enlighten me?
Thanks
