I finally got sick of seeing my SES light come on intermittenly. I bit the bullet and purchased a set of coils and platinum plugs. The procedure was alot easier than I thought. The car runs great now. I was wondering though, is there any way to determine which coil was failing? I still have the old plugs and coils but I could not tell which one may have been misfiring. All the plugs look the same. I was hoping to keep the old coils as a spare.