BMW Repair: Idling problems, intake hoses, cheap gasoline

Question
My 20 yr. son has a 94' 525I that has develpoed idling problems. The car runs great when you step on the gas it's just that it barely idles at stop. He cleaned the throttle body and there was a slight improvement but that was it. Is there a sensor or something he should be lookng at? He doesn't use cheap gasoline so we believe that's not the issue.  

Answer
Joe, make sure all of your intake hoses are good and not cracked or split. Take a long extension and tap on the idle valve under the intake manifold by the multi-connection coolant tube looking thing. See if the idle changes when you tap on it. If it does take it out and clean it with solvent. If this works please leave a follow up survey.
-Evan