hi all, i seriously need some help, ive got a 2003 typs s, when i start the car its idling on 2000 revs, then after a minute or two it drops the revs then starts hunting , from anything between 1000 and 2000 , i originaly though it may have been the battery as it was flat but ive fully charged it and the car is still the same, any help would be really appreciated.