I'm guessing you've got an idle problem? If so, have you bothered to have a look at your Idle air adjusting (IAA) unit (thats the thingy that the AAC is mounted on, the AAC valve operates it) If your AAC was dirty/clogged up then there's a mighty high chance that your IAA is going to be the same, and if that is the case it wont matter if your AAC is working or not.
Apart from being dirty it could also have a worn out spring inside it, you can adjust it but that might not solve the problem if it's totally buggered.