reving problem

[iwt5007]

I have a 99.5 a4 1.8t tiptronic and i was driving the other day when all of a sudden my a/c unit shut off and wouldn't turn back on......also my car then started reving when fully stopped. it would rev from under 1000rpm and then shoot to close to 2000prms about every 30 to 60 seconds....this also started happening as i was driving and became very annoying when it would rev when i was braking....when it revs, the back light for the a/c unit comes on faintly and then goes out once it stops reving.....my one friend suggests that either i have a boost leak or my idle control valve needs cleaning...any thoughts?

[biketsai]

Hmm, any codes? I would def first check for any visible leaks b/c that could cause the rpm to dip/etc.