Nissan Repair: pathfinder 1997 engine stalled, fuel pressure gauge, fuel pump relay

Question
My nissan pathfinder XE 1997 starts and runs fine but all sudden without warning the engine is cut off just like the key turns off. It stalled on highway (65,60,55 mile)or street(45, 40,35, 30, 20), and even at stop/park. But it starts right up with one key stroke without giving any gas paddle(NO waiting)and it runs fine again until the next stallimg.  No indicator lights appeared appeared on dashboard. It has been ongoing for six months. These are the following things have been done so far: major tune up, Distributor, ignition module and coil, relay ignition all have been replaced. throttle clean up and readjusted air intake. NO RELIEF IN SIGHT. There is no any abnormal indication on mechanic computer check up.
I need help!
chanpho

Answer
Chanpho,

Change the fuel pump relay for starters.  Second, hook up a fuel pressure gauge to see if the fuel pressure drops off when it dies.  You can connect the gauge to the fuel rail and set it on the cowl and then shut the hood on the hose.  Don't worry as there is enough room for the hose and this way you can face the gauge where you can see it when you drive.  Now, if the fuel pressure goes down just before it dies you will know that you have a fuel pump going out.  I say this since I asked that the fuel pump relay was replaced before we started.  If it never does it again it was the relay and if the pressure drops you need a new fuel pump.  If it dies and the pressure remains then it is an electrical problem related to the coil or distributor.  I know that you have replaced these so I stated the fuel pump would be the most obvious suspect.