If this is an F-series truck, that has the up and down arrows on the dash there is a fine mesh screen under the elbow where the fuel hose connects to the injector housing. A lot of times there is a tar build-up on it and it will not allow fuel to get to the injector. There is also an O-ring on the injector that could be bad and flooding the motor. Can you hear any fuel pressure when you shut the key off? If you do then you may have a vaporizer problem or bad injector. The L-series truck has the screen under an oval cover on top of the injector holder opposite from the fuel line.