About a year ago with about 100,000 miles showing and around 300 miles after having the dealer replace spark plugs on our Durango, it developed a slight hesitation when the motor was cool/cold. We went to our Florida condo shortly thereafter and in the Florida heat, it was barely noticeable. Covid brought us back to Nova Scotia, and we put it in our garage choosing to drive our 2006 Jeep Liberty. Well, I took it out a couple of weeks ago, and our cold fall weather brought the problem back with a vengeance. I did have it quickly checked out while in Florida, but there were, and continue to be no "codes" and the problem disappearing once the motor warms, we chose to not spend a lot of money trying to diagnose the problem. All that to say, the dealer has had the SUV, replaced the plugs, still no codes, and still a disappearing hesitation.
We love the vehicle, it still rides like new, but are very concerned when the border opens and we leave for Florida it will break down. The dealer is just now reaching out to the manufacturer for suggestions of what the problem might be. They have replaced the plugs, checked out the obvious problems, all to no avail. Has anyone else encountered similar problems?

 

As an update, we are picking the vehicle today with the problem still not identified. They have replaced the plugs and effectively redid everything that was done just prior to the symptoms began. They have repeatedly tested for codes, and have contacted FCA who apparently had no suggestions as to what creates the symptoms.
They think it "might" be some type of "converter'? to do with the transmission, but are not sure. But they say if that is what it is there should be codes. Plus, there is no way of testing it, and to replace it is an expensive procedure. They are saying that it seems to appear at 1500 to 1700 RPM in all gears except first. Also, they say that it should not represent a safety issue.
All that to say, we have spent a bunch of money and are no closer to getting it repaired. Although it is an 8 year old moderately high mileage vehicle, it still looks & rides like new that we would like to drive for a while yet given the expense of replacing it. I cannot believe we are the only people who have experienced these symptoms and that FCA had no idea of what it could be!