Stops and goes

When I am driving on the expressway in the winter my 2005 freestar will cut out like it is going to stall. It has not stalled yet nor has it been fixed yet. My dealership has installed a computer to read the problem however it cannot find anything wrong. The problem continues every winter usually when it is snowing. It is as if my car has the hiccups. The PCM was replaced with only 14 miles on the car and since then has been replaced along with the Mass Air flow sensor (twice). The Techs cant figure out what is wrong. The problem does not occur in the summer only winter and usually in the snow. It feels like something is missing or a sensor is not working properly for a second.