I have a '07 Grand Cherokee with a stock Hemi. Sometimes at idle the RPM's will stumble and almost shut off. I just swapped the air filter to a K&N and pulled a couple of spark plugs to check them out. They look healthy. What could be the issue?

If this was the Belvedere there wouldn't be any question. But then the Belvedere doesn't have variable valve timing, multiple displacement, mpfi and all that other stuff.