Have had the same issue for about a year now and I work at a dealership. I have had discussions with the mechanics regarding it and ran codes on the car. They had a crankshaft/camshaft code that ran twice, and that could be possible because are cop cars are KNOWN for camshaft issues.(Hence, always idling) However, my a/c compressor clutch pulley just took a shit, so Im replacing that this morning and Im HOPING its the compressor. Otherwise youre gonna be looking at replacing a cam or a crank.
Im just gonna ride it becomes a problem.