I have a 2001 Chevy Silverado 1500 4x4 5.3 I have replaced all four o2 sensors at the catalytic converter and replaced the fuel pump the fuel pump pressure regulator and it still want take gas it has a very bad hesitation. If you give it gas slowly at will go and then at time it wont. Please help me I'm about to go broke working on it. Thanks George

What is the fuel pressure reading?
Any codes or check engine lights?
What is the engine vacuum reading at idel and at 2K rpm?