2003 Outback misfires in the cold

subaru
outback

#1

When the temperature is below 20F our 03 Outback misfires to the point of stalling with smelly white smoke coming out the tailpipe and black particles on the ground.

I had it towed to our mechanic twice who could not get it to misfire. Of course it started up fine for them. I tried high test, dry gas, and a new fuel filter.