Probably just in front of, or on the front of the catalytic converter.
I had a problem with stalling with a 2000 Impala, and it was the oxygen sensor.
install 3.8 Chevy impala crank sensor passenger side , remove wheel and use pully to pull out crank shaft
Check
Symptoms of a bad oxygen sensor in a 2000 Chevy Impala 3.4 may include poor fuel economy, rough idling, and increased emissions. The check engine light may also illuminate, indicating potential engine performance issues. Additionally, you might experience hesitation during acceleration or unusual smells from the exhaust, such as a sulfur or rotten egg odor. If these symptoms are present, it's advisable to have the sensor checked and potentially replaced.
To change the fuel level sensor in a 2000 Chevy Impala, first close the gas and power lines. Remove the wiring and then drop the car tank. Remove the old fuel level sensor and replace it with the new one.
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Trouble code P0141 means:O2 sensor heater circuit malfunction (Bank 1 Sensor 2)
Left Side of the engine: in the sensor case attached to the vacuum hoses
could be the oxygen sensor. that's what it was on mine.
It has 4 of them screwed into the exhaust system/pipes.