I'd be surprised if that coating is still there. I wouldnt worry about it. If you are, just buy a can of throttle body cleaner. Works like carb cleaner but it wont strip this coating off. What some TB manufacturers do, is apply some form of epoxy to the bore in the area where the blade seals. When they install the blade, they'll back off the idle stop screw all the way, and open the blade and then let it slam shut. They do this several times so that the blade forms its own shape into the epoxy stuff and gives you a perfect seal. This is to make up for manufacturing flaws. Ive bored out TB's and machined my own blades before. It takes some special tricks to get the right shape out of the blade so that when it sits in the bore at an angle, it will seal properly around the whole perimeter. Even if you machine everything perfect, blade binding can still be a real PITA problem to fix. Ive had to spend hours with a tiny diamond file, sandpaper and a dremel to get rid of binding issues. The tiniest interference can cause alot of problems when the vacuum in the plenum pulls back on the blade and causes binding. So even if it doesnt bind when its off the car, it might when you bolt it on and fire it up. But Ive only seen this stuff in a handful of TB's. Carb cleaner will not remove this crap, so I dont know what it is they're so worried about.
