Fuel system lean - multiple codes - Help please

[sulsa30]

Hi, I have a 2003 525i wagon. It has 130k miles and I've never had any major issues with the engine.

I have a bunch of fault codes:

PO0313 - Misfire Detected with Low Fuel
PO0102 - Mass Air Flow (MAF) Circuit Low Input
PO1085 - Fuel Control Mixture Lean (Bank 2 Sensor 1)
PO1083 - Fuel Control Mixture Lean (Bank 1 Sensor 1)
PO0171 - P0171 System too Lean (Bank 1)
PO0174 - P0174 System too Lean (Bank 2)

I have installed new spark plugs, 2 pre cat oxygen sensors, cleaned out the MAF and checked for any possible vacuum leaks in the air intake system. The engine does have a leaky valve cover gasket which I am planning on replacing tomorrow. Might this cause the system to be lean?

The car drives fine, except if I let the car idle for a few minutes before putting it into gear. The idle gets real rough and acts like it will stall. Once I put it in gear it stalls.


I was going to replace the MAF sensor but before I drop a few bills on that, try to diagnose it better. Any suggestions? Thanks