P0171 Fault Code

[The_Limey]

So whilst waiting for parts to fix my current AC problem, The Money Pit decides to throw me a new and interesting problem. I pulled the P0171 code (system too lean - bank 1) for perhaps the fourth time today since buying the car in November. Normally the CEL shuts off after a few days and my wife reports no adverse symptoms (surging or lack of power) whilst driving the car.

Freeze frame information:
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Fuel Status = 0 byte
Engine Load = 48.235 %
Engine Coolant Temperature = 95 °C
Fuel Trim Bank 1 Short Term = -2.344 %
Fuel Trim Bank 1 Long Term = 29.688 %
Intake Manifold Pressure = 11.458 psi
Engine RPM = 2,510.5 rpm
Speed (OBD) = 51 km/h
Timing Advance = 13 °
Intake Air Temperature = 28 °C
Mass Air Flow Rate = 18.09 g/s
Throttle Position(Manifold) = 33.725 %
Run time since engine start = 457 s
Fuel Level (From Engine ECU) = 77.255 %
Distance travelled since codes cleared = 759 km
Evap System Vapour Pressure = -333.25 Pa
Barometric pressure (from vehicle) = 14.214 psi
Catalyst Temperature (Bank 1,Sensor 1) = 567 °C
Voltage (Control Module) = 14.249 V
Engine Load(Absolute) = 45.49 %
Commanded Equivalence Ratio(lambda) = 1
Relative Throttle Position = 21.176 %
Ambient air temp = 17 °C
Absolute Throttle Position B = 34.118 %
Accelerator PedalPosition D = 33.725 %
Accelerator PedalPosition E = 16.078 %




End of report.

I've looked into several threads on the forum which suggest the culprit could be anything from a dodgy MAP or O2 sensor, to an aging fuel pump. The AC debacle has cost me a bunch, and I'm currently unemployed. Without the luxury of just replacing parts until the problem goes away, could anybody help me join the dots up and make sense of what might be causing this fault code?

Edit: Since reading an article about how 02 sensors work and how to test them, I setup Torque on my tablet to plot a graph of the voltage outputs from both 02 sensors. I assume sensor 1 is upstream of the cat and sensor 2 is downstream of the cat. I'm also going to assume the upstream sensor is the one used for fuel trim, and the downstream sensor is used more for monitoring the efficacy of the catalytic convertor itself. Sensor 1 seemed to be oscillating between its minimum voltage and about 0.7V as the article describes. It also talked about introducing a vacuum leak or propane charge to the system in order to provoke a spike in the readings. I'm not sure if this is needed, or whether the oscillations are sufficient to rule out a fault 02 sensor?