P0101 Fault in 2003 Chevrolet 2500HD 6.0L Diesel: Symptoms, Diagnostics & Fixes

My 2003 Chevrolet 2500HD 6.0L diesel truck triggered code P0101 this morning while I was driving to work. After clearing the code during lunch and replacing the air filter, the fault has not returned. However, I've observed some intermittent symptoms: when braking or shifting through PRND321, the engine idle drops below 500 RPM for a brief moment before recovering. This occurs occasionally. Additionally, in Drive (D), the truck sometimes struggles to engage the correct gear. Research into P0101 indicates this code is often linked to airflow sensor issues, which may explain these symptoms. I've confirmed fuel pressure at idle—currently reading 50 psi at the fuel rail—and have ruled out major fuel system problems. While not a mechanic, I own an OBD2 scanner, fuel pressure gauge, and vacuum gauge, so I'm prepared to perform further diagnostics if needed. Tomorrow, I plan to disassemble the air box and clean the throttle body as a preventive measure. Any insights or experiences with P0101 in 2003 Chevy 2500HD 6.0 models would be greatly appreciated.