located at the throttle body... now just to help you out on saving money, once you find it, disconnect it while the car is running, if the car dies, the IAC (Idler Air control) is working fine.... now if the car stays running, that shows symptoms of a faulty IAC.... GL! oh yeah, one more thing.... if that's the zetec 2.0L common in those and the focus.. they had a know problem for the PCV hose going bad... (located on the back of the intake manifold) ... a vacuum leak that would cause. Which would lead to rough idles, or car possibly dieing