I have a 2004 trailblazer with about 120k on it. I notice the tailpipe was blowing out black soot specks on the ground. Don't know what this could be. I did do some research and i found out it could lead to a number of things i.e. intake, injectors, cat, tailpipe clogged etc. Can anyone give some idea on how to tackle this problem. Also, provide me with esimated cost if it is a intake/injector problem. Thx.

Kenny