have you actually physically checked if fuel is coming out of that injector, could be a fault in the line or the metering head. pull all 4 injectors and do a spray/volume test.
1. find 4 containers of equal size and tape them, all together
2. pop each injector into a container
3. pull the black wires from the coil to prevent any chance of a spark
4. pop the inlet boot off the metering head to gain access to the metering flap
5. bridge the fuel pump relay socket with a chunky bit of wire, relay is 67, 167 or 80, and pins you want are the 2 largest ones
6. smoothly lift the flap off its top all the way to fully open, then allow it to drop again (magnet helps here)
watch the spray pattern on all 4, and measure the volume delivered is roughly equal. if any are different swap injectors and repeat. if problem moves its the injector, if not swap the fuel lines over and repeat. If problem moves its the lines, if not its the metering head.
Before you crack loose any lines or injectors disconnect pump relay and move metering head flap to release the pressure, and wrap it in a rag before you crack loose. ideally you should leave it a few hours.
last test is injector leak, wipe the tips of all 4 injectors once you drop the flap and disconnect pump relay jumper wire then wait for at least 15 seconds, they should not drip
