The misfiring occurs at idle, and whenever I’m driving it. It runs very roughly. You can feel the excessive vibration while you’re just sitting there. I have the 4.3 liter V6 for an engine.
I noticed it was idling a little funny last week - it normally idles at 500 RPMs. Every so often, it would drop a couple hundred RPMS and bounce back - nothing dramatic, but something I noticed.