I have a new issue will my 03 Chevy 6.0. When the truck is cold it idles rough. Doesn't actually feel like a misfiring cylinder. In gear at a stop light the idle will drop below 500 rpm and the engine...
From what I've read, it could be sticktion(?)with one of the injectors. Arches diesel treatment has been known to eliminate sticktion. If you can't find it on the shelf at auto parts, I would try any diesel treatment. Pat