Hello. I have a 2004 Pacifica AWD 3.5L V-6. The last couple weeks, there is a thick white cloud of smoke when I accelerate. It only lasts about 2 minutes, then it goes away. When the car is idle, there is no smoke... only when I accelerate-- and only for the first couple minutes. It is very noticeable--I can see it in my rear view mirror. Of course, everyone says its a head gasket problem--I just wanted to see if there are any other possibilities. The car is not overheating, and the coolant is not low. It isn't just when it's cold--as it happened even on warmer days. If I shut my car off, go into the grocery store and come back out, it doesn't do it at all. It only does it if the engine has sat for a long time. I notice it in the morning, and when I leave work. (both times the car has been sitting for 8-12 hours). Any input would be greatly appreciated