When it’s cold the Wrangler runs like the cylinders are full of rocks and dies the moment you let off the throttle. It also leaves a huge amount of soot on the ground. To me, that screams it’s either running incredibly rich, or misfiring. It runs just fine after it warms up. Any other ideas? It’s got the 4.2.

This soot is after running just for the duration of the video above. The pavement is also wet, so the spot doesn’t seem as dark as it really is.