I would not think block exhaust, but I would take that throttle body apart or at least off and soak it in some carb cleaner. I would not trust those injectors either. As for being in the garaged covered, so was mine. The exhaust rusted sitting. Keep in mind, every time you start a car you get moisture in the exhaust, and just because I started it in the garage, I never got rid of the moisture. Never even thought about it. But do check your exhaust for blockage, but I don't think this is your problem at this point.