If IAC is working as described, it should be in working order. Unless the idling is out of specs and cannot be controlled, then the IAC is bad. A bad IAC would trigger a trouble code.
When IAC gets clogged with dirt, it sometimes takes a few cleaning session to get it in good working order.
Though the CEL might have gone off, the trouble code is recorded in the PCM and a scan would reveal what is it. It could be related to the problem.
The hose is part of air bypass and if it has collapsed, the amount of air is reduced and this can result in lower idling speed.
Thursday, October 28th, 2010 AT 2:06 PM