F5C Fuel System: High Pressure Pump Fuel Quantity Not Plausible At Low Idle. Check For Clogged Fuel Filter, Leakage In High Pressure System, Low Pressure Pump Red Hydraulic Circuit, High Pressure Pump Low Efficiency, Or Injectors For Tightness.
If Inadequate air flow is problematic, so clogged air filters, evaporator core air flow restricted, faulty blower fan motors, defective blower switch or faulty wiring or loose connections.