There is a good chance that your boost control solenoid has gone bad because you are having problems with the boost as well.
If it was your evaporative canister purge solenoid, you would likely have a rough or high idle. If it was the TCC, you would notice that the trans was not operating properly. The error code is telling you that one of those three things is not responding as commanded.
The best way to test it is with a Tech 1 or Tech 2, because you can command the boost control solenoid off and on and see if it responds correctly.
1999 540iA Sport
Former 93 SSEi Owner
Former 89 SE Owner