I would check your minimum threshold for your TPS, make sure it's going all the way below this, although that would typically cause slight choking due to extra fuel, just a quick check to make sure. Also, what are you using to control idle? Stock ECU? Things to check would be, make sure your EGR valve is closing all the way, make sure your PCV valve isn't sticking at all, etc. Could be a small vacuum leak coming from somewhere, takes a few for the stock ECU to compensate. Hard to really diagnose over the computer, but those are a few things to check.