you could try and remove the IAC and clean or kinda scrape off any carbon deposits off the screen. Don't spray anything on it to clean it scrape it off because you might clogg the IACV with the liquid. Like brake cleaner or carb. cleaner. Just dry scrape it off and reinstall and see if it helps anything. Also try running some sorta induction cleaner and like Phillez said check for any intake air leaks etc..vaccum. Also does your car have a power steering pressure switch for when you turn the wheel and the idle drops way down?