Idling at 1500 rpm?

My '86 325es is consistently idling at 1500 rpm. I believe it should idle closer to 800 rpm, right? All of my research has shown similar problems in which the idle speed will shoot up to 1500 and then swing wildly between 800 and 1500, but mine doesn't swing, surge, or otherwise behave oddly. It's just a steady 1500. Has anybody else had this problem and found a solution? Am I just missing something obvious? Thanks.