Error codes P0420 P0123?

1998 JEEP CHEROKEE
90,000 MILES • 2.1L • 5 CYL • 4WD • AUTOMATIC
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SCHANT000
These error code were shown when tested by obd11 and I'm trying to fix the problem trying each suggestion but not sure if I'm even doing it right. Also note that while driving the cat converter fell completely off and still made it home afew blocks later. So the re is overheating that occurs every time it's driven, hesitant startup needing to pump gas to turn over and now most recent stalling out while driving usually when hot but Guage not working properly to inform me.
Jul 7, 2025 at 9:56 PM
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STRAILER
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So the first code is because the catalytic converter is bad/fell off so you will need to repair that issue. The "pump the gas" and stalling issue can be the second code.

Code P0420 - Catalyst System Efficiency Below Threshold
Code P0123 - Throttle Position Sensor (TPS) Circuit High Input

I would check the wiring to the TPS and if okay replace the sensor, here is how in the images below. Also, please start a new thread for the overheating problem. Check out the images (below). Please upload pictures or videos in your response.
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Jul 8, 2025 at 8:27 AM
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