I have a 99 f150 with a 4.2l v6 that is running very rough, sometimes it will starts sometimes it will take it a few times to start. I hooked up a fuel pressure tester and I was only getting about 20 pounds of pressure and I supposedly need 45-50. I changed the pcv valve fuel filter and fuel pump and I still can not figure out the problem, it idles very rough too and sometimes it will just die. When I press the gas there is a very bad hesitation. I'm at a loss of what else it could be. Help please?

 

Fuel pressure regulator?

 

That's the same problem I have with mine..replaced the fuel filter and fuel pump..pcv valve worked fine..