P0507 and having a high than normal vacuum when you say PCV it the crankcase ventilation valve that needs to be replaced, Audi recalled the crankcase valve because it was setting a P0507
the one listed as Number 1 this would be the cause for the high vacuum leak, unless you have a open intake valve, if that was so the engine would barely run.As for the P0171 and this gets past most everyone when it comes to a Audi, The airfilter if it is not seated correctly it will set a P0171. Audi even put a TSB on this hard to believe but its true
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