chrysler grand voyager keeps cutting out while driving?

hi. i have a chrysler grand voyager 2.5 diesel and it keeps cutting out while i'm driving. it will cut out at any time with no warning. there are no warning lights and no faults found. it is cutting out more and more. now when i drive only up the road it cuts out about 6 times. it will start straight up again only to cut out after a short distance. it will start up and keep running while it's stationary. any idea whats wrong?