I had this problem

Changed the Relay for a later white one....
still had cutting out problems. Changed the crank sensor (or pulse sensor). The wires were broken!

VW charged me £113 for a new one on trade! still flippin expensive

You have to take off the engine mount bracket which longs your life out abit

Old against the new pulse sensor..

EDIT: went out for a long drive and it has not cut out yet (thank God)