P0171 P0420 P0430 Fault Diagnosis - 2003 Ford Expedition 4.6L 2WD with Idle Drop and Power Loss

My 2003 Ford Expedition 4.6L 2WD engine runs smoothly when cold, idling at approximately 1000 RPM. However, as the engine warms up, the idle drops to around 700 RPM. Under light throttle input (past 1/3), power delivery flattens out significantly. Freeze frame data from five instances when the Check Engine Light activated shows the following OBD2 fault codes and sensor readings: OBD2 P0 Codes: P0171, P0420, P0430 - Fuel System 1: Constantly 'CL' (Check Limit) - Fuel System 2: Not applicable (NA) - Calculated Load Percentage: 92.94% → 79.61% → 50.98% → 90.20% → 71.76% → 88.63% - ECT (Engine Coolant Temp): 89°C → 89°C → 90°C → 92°C → 90°C → 94°C - STFT B1 (%): 3.13% → 7.03% → -6.25% → 5.47% → -2.34% → 9.59% - LTFT B1 (%): 24.22% → 29.69% → 14.06% → 24.22% → 8.59% → 24.20% - STFT B2 (%): 0.00% → 1.56% → -0.78% → 3.13% → -4.69% → -2.34% - LTFT B2 (%): -12.50% → -14.64% → -9.38% → -10.16% → -9.38% → -12.50% - Engine RPM: 2608 → 2970 → 1278 → 2723 → 1434 → 2621 - Speed (km/h): 94 → 37 → 59 → 100 → 54 → 61 - Spark Advance: 20° → 18° → 38° → 23° → 31° → 21° - IAT (Intake Air Temp): 6°C → 18°C → 7°C → 17°C → 21°C → 15°C - MAF (Mass Air Flow, g/s): 78.01 → 81.22 → 18.77 → 70.98 → 25.00 → 63.62 - TPS (%): 61.96 → 45.88 → 22.35 → 56.08 → 27.45 → 49.40 - O2S B1 S1 Voltage: 0.75V → 0.10V → 0.87V → 0.14V → 0.80V → 0.09V - STFT B1 S1 (%): 3.13% → 7.03% → -6.25% → 5.47% → -2.34% → 8.59% - O2S B1 S2 Voltage: 0.79V → 0.12V → 0.82V → 0.21V → 0.72V → 0.25V - STFT B1 S2 (%): 99.22% → 99.22% → 99.22% → 99.22% → 99.22% → 99.22% - O2S B2 S1 Voltage: 0.76V → 0.90V → 0.76V → 0.11V → 0.26V → 0.78V - STFT B2 S1 (%): 0.00% → 1.56% → -0.78% → 3.13% → -4.69% → -2.34% - O2S B2 S2 Voltage: 0.82V → 0.83V → 0.19V → 0.37V → 0.55V → 0.75V - STFT B2 S2 (%): 99.22% → 99.22% → 99.22% → 99.22% → 99.22% → 99.22% Fault Code Interpretations: - P0171: System too lean (Bank 1) - P0420: Catalyst system efficiency below threshold (Bank 1) - P0430: Catalyst system efficiency below threshold (Bank 2) I recently replaced the fuel pump and filter. However, during full-load operation, two exhaust hoses connected to the EGR EVP are repeatedly blowing out — suggesting excessive backpressure. I suspect the catalytic converters may be clogged and blocking exhaust flow. Additionally, I incorrectly installed a new PCV valve on the wrong valve cover, resulting in dual PCV valves and abnormally high vacuum levels for an extended period. I'm unsure if this installation error contributed to current issues. I would appreciate any insights into possible root causes — especially regarding catalytic converter failure, vacuum leaks, or MAF/TPS sensor performance. Thank you, John