Idle speed has been computer-controlled and not adjustable on all cars since the late '80s / early '90s. When it's wrong it's due to a vacuum leak, sensor problem, or something related to spark or fuel. If the battery was recently disconnected or run dead, there are conditions that must be met before the Engine Computer will know when it must be in control of idle speed.
You know the EGR valve didn't fail that many times. What symptom are you working on, or what led you to that valve?
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Friday, November 29th, 2013 AT 5:54 PM