My Grand Cherokee is idling rough – could it be spark plugs?

[hertawintle]

Rough idle, hesitation and a drop in mpg fit worn plugs, but they fit a failing coil just as well. On the 3.6 Pentastar the plugs sit deep under the coils, so it’s worth having them pull the codes first and check for a misfire on a specific cylinder. That tells you if it’s plugs or a coil.