Not sure I agree with the previous statements. My 2000 GT has an IAC with the black vent. My 2003 GT has the IAC without the black vent. There is a difference in the tune. For a application with the black vent, the initial starting air is supplied by the black vent. Purely mechanical. No PCM action required.
For an application without the black vent, the PCM has to command the IAC to open to supply startup air.