P0102 OBD2 Fault Code on 2000 Cadillac STS: Diagnosis and Solutions

Hi everyone, I'm experiencing a persistent P0102 OBD2 fault code on my 2000 Cadillac STS. According to GM's documentation, this code indicates a 'low frequency' airflow reading from the Mass Airflow (MAF) sensor. I've already replaced the MAF sensor and thoroughly cleaned it — even installed it directly onto the throttle body to rule out any leaks between the filter housing, MAF, and throttle body. Despite these steps, the P0102 code remains unchanged. No other active OBD codes are present except for history records. I'm now considering whether I can measure voltage or resistance at the MAF sensor connector. Is this possible? What diagnostic steps should I take next? Additionally, during idle, I've noticed a metallic rumble coming from the catalytic converter. Could a loose monolithic ceramic component inside the cat be causing the P0102 code? Or could restricting exhaust flow (e.g., due to backpressure) lead to incorrect airflow readings and trigger this error? Any insights or experiences with similar issues on 2000 Cadillac STS models would be greatly appreciated. I've gone through all basic checks — any further troubleshooting tips?