Fiat Fiorino 1997

Please, if someone can help me with information on how to fix the problem I have with my fiat fiorino from 97, the problem is that I always jump because it goes out and does not want to turn on, it already uncovers it and the head is fine, the starter engine is fine, battery too that is what the mechanics tell me, the electrician also told me that everything is fine, a mechanical alleged k And I "arrange" but at two hours of shooting more or less on the road I went out again and I no longer want to keep spending silver where all the mechanics and none gives solve, help me x fa ... Thank you

do you stop when you walk? in relief? in cold? hot? Sounds like? The start is heard?^Or does nothing sound when you fail? Did you check that the terminals are not isolated? The herratic relief?