I have a 2004 Ford Explorer Eddie Bauer V8. One day while driving the vehicle lost engine power and eventually stopped. I got the vehicle back to my house and diagnosed that the fuel pump was faulty. I have replaced the fuel pump and fuel filter, however now the vehicle does not start at all. I have checked the fuel lines, the injectors, the spark plugs, and the fuel pressure sensor to find the are all in good working order. A strange thing I’ve noticed it that when I allow the car to sit(roughly a day or two) the fuel pressure seems to build up enough to where the engine almost fires. I have yet to test the fuel pressure being as I don’t know which location to hook into. Any assistance would be much appreciated.

Would the engine need to be running to get an accurate reading or should I just check what the current pressure is?