Wifes Patriot has rough idle but does not throw codes.

[akelts]

Her car has been pretty well maintained (by me) since we purchased it new. Its a 2009 with the 2.4 liter and CVT transmission.

Since we moved to Leadville CO last fall it has developed a loopy idle and sometimes stalls or lurches if you don't let it warm up for a few minutes before putting it in gear. Not sure if the elevation here has anything to do with it. Leadville is at 10,200 ft. The rough idle smooths out if it is put in neutral so maybe the engine mounts are bad, but that should not cause it to stall.

I cant find anything wrong with it. Took it to a repair shop and they could not identify the problem. It never throws any codes even with the stalling.

I am going to start by looking at spark plug condition and maybe checking the fuel pressure. Any ideas what I else I should check?