That is great info. This is either a PCM or a sensor that is feeding the PCM faulty info.
So this is called open and closed loop. Basically the engine starts in open loop and runs off a preprogramed set of parameters based on the temperature sensors.
Then the PCM monitors the engine coolant temp and as soon as it is up to operating temperature, it switching to closed loop and monitors the o2 sensor data as well as the other sensors to fine tune the air fuel mixture.
See below for more detail.
What I would do to confirm this is the issue is unplug the o2 sensors and see if this does not happen at all. This should keep the engine in open loop and that would prevent it from acting up.
Do you have a scan tool that we can monitor o2 sensor data? If the o2 sensors are telling the PCM that it is rich then the PCM should be adjusting but if it is not then the PCM could be the issue. However, the PCM may be trying to adjust this but if the injectors are leaking then that would cause this as well. The only thing that doesn't support this is that you would think a leaking injector would not stop just because an o2 sensor is unplugged.
This is why we need to confirm that when changing the state of open to closed loop and back that the issue starts and stops. If it does then the PCM is the issue since you already replaced the o2 sensor.
The only thing that gives me pause is the o2 sensor that you replaced is also faulty but that is unlikely but not impossible.
Let me know if you have questions on this.
Thanks
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Saturday, August 14th, 2021 AT 6:04 PM