volkswagen transporter 1997?

i have a volkswagen transporter year 1997, when i switch on it start. but after 10 minutes while driving and when i changed gear it stops and soon after it restart its ok then the same problem of stopping the engine go on, and then it did not start. can you help me to fix that problem. The mechanic has already change a new injection pump and a complete servicing has been done.

marsel
April 2009