V70 R leaves during the journey

Good day, I often have the problem that my car ( V70R year 2003 ) runs out during the ride. Sometimes it can only be started again after several organs, but most often it starts problem-free. In the workshop the contact plate of the ignition lock was changed as the first diagnosis. But that remained without success. A fault code was not shown. Vehicle is an automatic. Does anyone have a suspicion? Greeting R-driver