Kit Car wit' da' 5oh'

Please help me. My 91 Mustang has been doing a lot of work, but the idling is unstable. I think the fuel is rich. Please tell me how to fix it. I've tried many things but can't fix it. As the water temperature warms up, the idle will go up and down. When I hit the accelerator, black smoke comes out.
The replaced part is
・distributor
・spark plug
・spark plug　wire
・coil
・injectors FOTE-D5A
・MAF
・BAP
・O2 sensor x2
・TPS
・IAC
・ACT
・ECT
・fuel tank
・fuel pump
・filter
・pressure　regulator
View: https://youtu.be/h3wNS9SllME?si=KXrWoeikD7zq7CRq


At about 9:30 seconds, the engine starts idling up and down and the engine stops.
View: https://youtu.be/mZocYssj7iY?si=IRb6XFaCTTOFQWdT


Even if I check the No. 1 spark plug wire with a timing light, the idling will be so erratic that the timing light won't respond.
View: https://youtube.com/shorts/I9sbMwCajng


black　smoke
Please provide information on repairs.

gkomo said:

Are you able to run codes?

Click to expand...

This is a kit car equipped with mustang GT engine 5.0HO. engine is normal　　There were no codes, but once I got 12, 18, 26, 42, and 92.

gkomo said:

What are your spark plugs gapped at?

Click to expand...

NEW pulg NGK UR45(6945) Gap.059" (1.5mm)

Noobz347 said:

• Code 12 – Idle Speed Control (ISC) / Idle Air Control (IAC) system not controlling idle properly (high RPM)
  • This could indicate a fault in the Idle Air Control (IAC) valve, vacuum leaks, or a problem with the Throttle Position Sensor (TPS).
• Code 18 – SPOUT (Spark Output) signal open or loss of tach input to EEC-IV
  • This means the ECU is not receiving the correct ignition timing advance signal. It could be due to a disconnected or faulty SPOUT connector, issues with the ignition module (TFI), or a problem with the PIP signal from the distributor.
• Code 26 – Mass Air Flow (MAF) or Manifold Absolute Pressure (MAP) sensor out of range
  • Depending on whether the vehicle has a MAF or MAP system, this code indicates a problem with airflow or manifold pressure readings, possibly due to a faulty sensor, wiring issue, or intake air leaks.
• Code 42 – HEGO (Oxygen sensor) indicates system is rich
  • This means the oxygen sensor is detecting an overly rich air/fuel mixture. Potential causes include a bad oxygen sensor, excessive fuel pressure, leaking injectors, or a faulty Engine Coolant Temperature (ECT) sensor.
• Code 92 – HEGO sensor indicates system running rich (Left side on dual exhaust systems)
  • Similar to Code 42 but specific to a dual exhaust system. It suggests that the left bank is running rich, which could be due to the same issues: bad O2 sensor, fuel pressure regulator failure, or injector problems.

Next Steps:​

• For Code 12, check for vacuum leaks and the ISC valve operation.
• For Code 18, inspect the SPOUT connector and ignition module.
• For Code 26, verify MAF/MAP sensor readings.
• For Codes 42 & 92, check the oxygen sensors, fuel pressure, and for leaking injectors.

I would disregard codes 42 and 92 for now. Concentrate on 12, 18 and 26.

Is this an A9L ECU? Where did the harness come from?

Click to expand...

thank you.
・I checked for vacuum leaks with smoke.
There is some leakage from EGR, but I think it's okay.
IAC control valve has been replaced.
・Remove the SPOUT connector, adjust the ignition timing to 10 degrees, and input SPOUT again.
The distributor has also been replaced.
How can I test it?
-MAF/BAP sensor has also been replaced.
・I also replaced two O2 sensors. The fuel pressure regulator has also been replaced, and the injector has also been replaced (FOTE-D5A)
could not be described