My dad has one of these that he uses for our business. in the past year it has been to the shop many times for what seems to be the same problem. We will go to start it and it will just crank and crank without turning over. And other times it will start just fine. A Few times while driving it has just died and then proceeds to do the above. 3 different shops have changed things like battery, coil, and 2 computers, but none of these things have done anything to it. It always seems to leave us stuck somewhere. What could be wrong? It has the V8 in it.