93 Voyager sudden engine stop during run

There was no help up to now from garage or special electrical service. My 2.5 l gasoline fuel injection driven Voyager stopps ignition without any influence during normal running on highway or in the city with hot motor or just started. Sometimes a restart was feasible directly after the stop but only via the starter not by jumpstart. But sometimes a restart was only possible after 1 hour. Failure read out of the board computer showed no indication. During that time there was no current on the coil + pole, a direct connection to the barttery + could not solve the problem. A two days run of the enine in the garage with oscillator on ended up with no stop of the engine, two days later in normal trafic the problem occured again.
Does anybody had similar problems, can anyone provide me with a good advice?
Thank you in advance for your engagement