his PCM is not actuating the IAC to maintain engine speed.you really don't want to manually change the idle via the set screw. The reason it is capped is becuase of the computer makes the adjustments needed. When it is dieing, if you put the trans in neutral does it stay running, or does it continue to die?
This would be a temp fix so he could keep driving it until he can get the parts replaced.
I ran mine with no IAC for about 8 months, and used the set screw to adjust idle. it will not damage his vehicle in any way.