When I removed the throttle body for cleaning, I noticed quite a bit of wet looking carbon deposits in the upper manifold. Adding cleaners such as Seafoam to the fuel will not take this out, since it is well above the injectors. I've seen shops set up an IV kind of drip in the intake rubber hose and run Seafoam at a slow drip with the engine idling for 30 or so minutes. Any thoughts on this method vs removing the upper intake and manually cleaning?