With the engine (fuel pump) running, check fuel delivery by cracking open the line nut above the pressure valve on the pump head for all four injectors (one at a time); the amount of fuel delivery should be equal. If you don't have fuel or dribbling fuel, swap out the pressure valve with a known good one for the cylinder in question.
The injectors are also known to get debris/rust in them and cause problems with incorrect spray patterns or sticking that will create a rich mixture as well (injector repair parts are NLA).
Never remove the suction valve disc with a magnet, there is a special tweezer tool to use for that procedure. Damage to the pump will occur if you do not use the tool.
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