2002 Ram 4.7 L engine odors at cold temps

I have a 2002 Ram Q/C with a 4.7 L engine that stinks up the cab with an exhaust/gasoline type odor when the engine's warm and idling and the outside temperature is below -20 C (it was -31 here this morning in manitoba). It's done this since it was new, but the Dodge dealer could never replicate the problem and so was never able to fix it despite several visits to the shop (when it was on warrenty). Anyone suggest what the source of the fumes could be? Malfunctioning/frozen EGR valve or something similar?

There's a hose on the back of your air-breather box that directs crank-case gases through the 'carburator' system that gets disconnected when the housing is removed to change the breather filter. Look at the back of the air-breather box on the top of the engine and make sure that the hose is firmly connected.