Our 99 Outback has an intermittent obd2 code p1507 - "engine idle control failure (failsafe)" - accompanied sometimes by poor performance and regular misfire. Changed the coilpack and wires, and replaced the idle air motor; no change. If I stop the engine, and restart, the misfire disappears (although the check engine light usually stays lit). Has anyone had similar problems and found the cause? Any help would be appreciated.