I don't believe it is a fuel related issue as I'm using winter blend fuel along with an additive. I've had instances in the last 2 winters of gelling in extreme cold even with additives, so I've had first hand experience with cold weather fuel issues.

I plan to get at it this weekend when I'll have some time to drop the wheel liners and test the plugs. I'll have to stop by the local Autozone and see if they'll scan for stored codes. My only concern with testing and/or replacing the plugs is corrosion and possibly breaking one off. I've owned the truck since new and it has 6 Wisconsin winters, so it has seen its fair share of road salt. If I do have to remove plugs, should it be done on a warm or a cold engine and would soaking them with a penetrating oil (like PB Blaster) be of any value?

Also, where is the air intake heater located ? I'll test that as well.

Thanks.