1992 f150 flareside wont run plugs getting flooded with fuel

I am working on a 1992 ford f150 flareside pickup 5.0l this truck has 42psi with key on not running when cranking engine holds 42psi but when you releases key from start position to key on engine off fuel pressure falls off i checked by pinching lines to see if returning to tank but it is not any ideas why this is happening there is no fuel leak externally under truck or on intake area tried to let sit over night and install plugs in morning started with gas pedal being moved repeatedly but only for 2 minutes or less running really rich finally stalled could not start again..........plugs soaked in fuel? thanks in advance any ideas greatly appreciated

I would start by testing the fuel pump relay. If the relay is stuck closed then the fuel pump may keep running. If you dont have spark then the fuel wont be burt and the plugs could be soaked. I dont know how well this will help you but the fuel pump relay is mounted Under hood, driver side, upper engine area, rear of air filter housing, mounted on wheelwell. It will have a yellow wire, light blue with orange strip wire, red wire and dark green with yellow strip wire.