Audi A4 3.2L with P0172 and P0175 Codes: O2 Sensor or Fuel Pressure Regulator Fault?

Hello, I own a 2009 Audi A4 3.2L with persistent DTCs P0172 and P0175 indicating both Bank 1 and Bank 2 are running too rich. Previously, the vehicle had multiple misfire codes, which led me to replace two fuel injectors — later upgraded by a friend who works at an Audi dealership to replace all six injectors. After replacing the fuel filter, installing new spark plugs and coil packs, the misfire codes disappeared, but P0172 and P0175 remained. The car ran poorly for about a month before I could afford further repairs. I'm concerned that prolonged operation under poor conditions may have damaged other sensors. Online forums suggest O2 sensors are commonly involved in these symptoms. During a previous diagnostic session, my friend found the fuel pressure regulator/sensor to be faulty. I plan to replace this component tomorrow and would appreciate any additional suggestions or diagnostics to confirm the root cause. Latest Freeze Frame Data: ------------------ Fuel Status = 0 byte Engine Load = 32.941% Engine Coolant Temperature = 85 °C Fuel Trim Bank 1 Short Term = -9.375% Fuel Trim Bank 1 Long Term = -28.125% Fuel Trim Bank 2 Short Term = -7.812% Fuel Trim Bank 2 Long Term = -28.906% Intake Manifold Pressure = 5.802 psi Engine RPM = 698 rpm Speed (OBD) = 0 km/h Timing Advance = 0.5 ° Intake Air Temperature = 30 °C Throttle Position (Manifold) = 13.725% Run time since engine start = 350 s Fuel Rail Pressure = 561.296 psi Barometric pressure (from vehicle) = 14.214 psi Voltage (Control Module) = 14.218 V Engine Load (Absolute) = 39.216% Commanded Equivalence Ratio (lambda) = 0.999 Relative Throttle Position = 4.706% Ambient air temp = 25 °C Absolute Throttle Position B = 13.333% Accelerator Pedal Position D = 14.902% Accelerator Pedal Position E = 7.451%