Check Engine Light On problems of the 2002 Nissan Pathfinder

The first time while driving the Pathfinder in regular driving conditions, the engine stalled at approximately 30 mph. To restart the engine I had to put the transmission in neutral and turn the key all the way off and then restart the vehicle. The second time this happened I was driving again the same day, cruising along at about 50 mph in traffic, and the engine died again with no warning. The instrument cluster showed all the typical "dummy lights" after the engine failed the first two times. When we parked the Pathfinder we could smell gas at the rear passenger door on the drivers side. We took the Pathfinder to the shop for repair. Fuel smell was corrected by installing a fuel pump seal and the fuel pump system was reseated, and reinstalled after an incorrect installation by a previous mechanic. After receiving the Pathfinder back fro our shop, the engine died again while sitting in a parked position running in an idle state. No instrument cluster lights came on when engine died this time (the 3rd time), no check engine or codes displayed. Then while driving again at 50 mph in normal driving conditions the engine died again, no indication of electrical issues, no flashes in headlights, interior lights, no flux in the hvac fan, nothing. Tachometer dropped to zero with no other indication the engine died, no vibration, no jerking. I put the transmission in neutral, shut of the key, and try to restart with no success. I coasted the car to the side of the road and turned the key off and removed it from the ignition and then re inserted it to restart the Pathfinder. Again, no check engine lights, no codes, nothing to indicate a problem. I purchased this car used only days ago 11/30/2014, and it has spent everyday in the shop trying to resolve this issue. It has only 96540 original miles on it, and is a very clean vehicle.