My car vibrates at a stop in drive or reverse after I have been driving 30+ mins, goes away if I turn ac on (raising rpm by a couple hundred) rpm still stays stable while vibration occurs, everything else seems fine. Has anyone who's had this found a fix? My theory is maybe the idle rpm was set low at the factory to save gas and they estimated a bit too low and then when the tcm does it's "learning process" if you happen to take mostly shorter dives not ever getting the engine up to its most efficient temp then when it actually does the idle drops accordingly and causes the vibration, or at least thats what I'm hoping.. Gunna unplug the battery for a while tomorrow and hope it can relearn my driving and fix it.. It has powertrain warranty but I don't want them to do just enough to limp me past the warranty and leave me screwed if it is torque converter or transmission related. I want to know as much as possible before I go in so that I dont get taken advantage of.