I have been experiencing random stalling and difficulty restarting although it seems to be getting more frequent. To date, I have replaced the pump, fuel filter, relay and cleaned the injectors. The problem persists and I am wondering if its the fuel pressure regulator located on the fuel rail? Typically, the issue only occurs after the car has warmed up. If the problem occurs and I allow the car to sit over night, it will fire up fine. Any related advice is greatly appreciated.

 

also consider the fuel injector relay - located up under the fan schroud. it could be the pressure regulator but normally those cause leak down over time making cold starts more difficult. pull the vacuum line off and see if any fuel leaks out as a quick test.