grinding noise in idle?Like the title says, i adjusted my idle the other day to be at about 700 so i can here the cam that low and its surging alittle so im gona put it at like 900, but when it dies down to 600 and shoots itself back up, i hear like the very light grinding/sratching noise from the engine or exhaust maybe, sounds really bad, its not loud though, at first at a light i thought it wasent my car but i kept hearing it so it is my car but idk what it is, and sometime when i lauch out of first i hear it, anyone have any ideas? should i not drive my car hard? I cant not drive it at all though, i NEED my car
