About a week ago my check engine light came on. Went home and hooked up the code reader and the code was p0300, random misfire. So I replaced all of the lower bank plugs with news ones from the dealership. Code went away but now it's idling @ 500 instead of the normal 600 and its fluctuates between 500-600 while sitting at red lights etc. the exhaust doesn't have a smooth tone like it should. So I just cleaned the throttle body but still has low idle.