The only injector cleaner I've had any luck with is Chevron Techron, not cleaner with techron, but plain techron. I've used an assortment of others, including Redline whose products I usually like, but without any sucess. But your symptoms don't sound to me like an injector problem, could it be the idle control valve, they are something of a problem, I have had to replace mine twice on my 85 535i, albeit with used ones which may explain the twice factor. Mike W.