I have an 04 ford ranger 4wd with a 4.0 motor in it about a month ago it quit running and i was pretty sure it was the fuel pump so i replaced it. I had problems with it starting after doing this so i replaced the fuel filter and im still having problems with it. i got it to start and run good if you take the air filter off and cover the breather with your hand. If you dont do that it will start but when you push down on the gas it boggs down and even dies. I have heard this could be a mass air flow sensor or even an o2 sensor all i know is im getting tired of replacing parts and not finding the problem any insight will help thanks