My Cougar was running pretty well (long story) before I pulled the engine for rebuild. My injectors look pretty clean...I'm not sure what they are supposed to look like when brand new. The little top hat things on the intake end are slightly discolored, but aren't crudded up at all. I can still see the four little pin holes on every one of them and I have no reason to believe any of them are non-functional. Is there any reason I might need to replace some (or all) of the injectors? Comb. chambers all looked about the same....a bit of carbon, but the stuff wasn't 1/4 inch thick or anything. What do y'all recommend?