Got a 2006 Durango with 5.7 hemi. Engine began to run rough couple weeks ago until engine warmed up. No code with my old obd II but had experienced this before and dealer replaced the EGR several years ago and problem solved(old reader would not read code at that time either) 1. Replaced EGR valve with new and rough/misfire continued. Purchased new obd II and found P0304. Replaced #4 coil pack and both spark plugs and cleared code. Next morning with cold engine rough idle and code returned, again only until engine warmed up. Next day with cold engine ohm tested injectors #2 & #4, both identical at 11.8 so swapped cylinders, engine ran fine and no code from start and over several mile drive. Next day as test started cold and rough idle returned only this time P0304 only showed as pending, not stored code and as soon as engine warmed again it ran fine (ambient temp >50 where previously 40-45 range). What is next? Checking the wires and clips to the PCM for resistance when cold? I don not believe it is mechanical as it smooths out upon warm up. Anyone with thoughts out there? I do plan on running a compression check to eliminate mechanical problems (valves and valve rings, etc) and also look for vacuum leaks at cold start, i just don't want to keep throwing money at it hoping it will go away, and that includes taking it to a dealer who would spend many hours diagnosing and testing the same components that I can (at no cost). I have checked and there is no technical bulletin for similar problem, but that does not mean that dealers have not reported similar problems, hence this inquiry here in the forum.