I'm wondering about this as well. I have an 11 GC Crew with 78K miles. I've already had it into the dealership for a misfire on cyl 4, and they replaced the heads. Now I'm getting another MIL that again says O2 or misfire, and the van is doing the idle fluctuation and feels like it's misfiring. Taking it back to the dealer on Wednesday, but would like to see an answer to Kevioll's post above. I don't want to do O2 sensors if that's not the problem.

 

I've noticed i'm now getting some hesitation when accelerating before the engine has warmed up. Feels like running out of fuel. No check engine light. I ordered new 02 sensors. I'll post the results when I install them.