Have a 2005 Chevy trailblazer that has a rough idle..I have changed the plugs and cleaned the throttle body don't know what else do to..any suggestions?
air filter restricted maybe.
Changed that too...sorry didn't mention that
possible small vacuum leak somewhere.
I've noticed that it idles rough when in reverse or drive only and it's not constant it's kinda intermittent
That's because the load increases on the engine and makes the problem more noticeable, I still think you have a small vacuum leak somewhere