cutting our problems

Hi all just joined up so here goes , bought mondeo 2.0 tdci titanium 08 , 3 weeks ago and in that time the car has cut out on me probably around 7-8 times mainly reversing off drive etc but it has cut out twice whilst ive been driving , which is a bit scary espically if the kids are in, just wondered if anybody had a problem like this, my m8 who is a mechanic put it on his diagnostic machine and came back with no problems hes going to check it again on saturday so im just hoping it stores some kind of code .