I pulled out my intake manifold last week in order to get access to the thermal control valve for installing new silicon vacuum lines. (I also figured that a check up and cleaning of the VOD was in order anyway.) I would like to give the intake manifold a good cleaning and possibly even spray coat it with something to make it look nice and new. I think the exterior is easy enough to deal with, but my real question is how to handle the inside. I've noticed what looks like a very baked on layer of carbon deposits on the inside walls of the manifold ports to the cylinders. I guess my first question should be: Does it even matter? (Perhaps I should just leave it as-is.) If the consensus is to clean it while it is out of the car, then can anyone offer some suggestions on what might remove or help dissolve this stuff?