idle speed on 1993 Mercury Cougar

this car idle too fast, can you explain what controlls the idle speed?

Asked by for the 1993 Mercury Cougar
There are several things that control the idle speed, the idle air control motor is commanded by the computer to control the idle speed, but if the power steering switch is stuck, or if there is large vacuum leak or if the idle motor it self is stuck, these all can cause a high idle as well as several other things. Best to pull the codes and really determine what the problems is, and not just guess, unless you have money to burn.