smoking x5!....any ideas?

[gitchies]

Wow strangest thing happened this morning...it was cold, very about -20 degress before windchill....got in the truck, started as normal....after driving for about 2-3 mins...i can smell exhaust burning, like burning oil...i can see this huge cloud following me..suddenly the car seems to want to shut off, everything flickers on and off..service engine light flashes quickly...i stop the truck turn it off...check to see if i'm losing fluids or anything...nothing, just the exhaust is smoking!!!! i start it back up again, seemed fine, so i drive.....seemed like a power loss again....keep driving and back to normal?....strange i thought...would could cause this? Exhaust plugged? then melted the ice off?