This might sound silly, but a friend of mine is fighting a 06 charger with the same problem, we been looking at everything on all sensors and stuff.. It runs light crap on cold start, falls on its face when giving it throttle, let off it idles throttle again falls on it face and backfires once sometimes more, does this till it runs for about 2-3 minutes, and runs fine, Seems like its about the time it goes into closed loop and o2 sensors start taking over. Anyway it stinks bad too when running. Today we think we found it. Some how Diesel fuel got mixed in with the gas. Think about it. cold start diesel wont burn until combustion is high or hot. so on cold start the fuel mixture is preset before closed loop, and its not vilatole enough with cold engine to fire properly especially under heavy throttle because the more throttle the more fuel(which is not all gas) so it cant ignite properly. about the time it goes into closed loop or close to it the combustion chamber is hotter so it starts burning the fuel better and the 02 sensors take over to control fuel per the senors readings, adjusting now for proper control.. Thougt maybe might help you... Wouldn't hurt to pump some fuel out thru the fuel pressure test port and look at it and let it set to see if its not mixed with something, I've been told street diesel has a green tint to it. and farm diesel has red. gas is yellow. maybe the tank where you got gas might have got mixed, I have seen this at a station in our town a couple of years ago.. They did put gas in underground diesel tank or vice versa, Anyway if you still got the problem might check it out Mike