Chasing cel and intermittent idle lope

[Fishwrench]

New to the forum, first post and happy to be here. 2008 impreza hatch, 2.5i. Have been chasing for a while. Started out with a p0171 lean code after a road trip. What has been done: maf, pre cat o2, egr, plugs, wires, pcv, checked/cleaned injectors, checked fuel pump and swapped with a spare, ive also smoked/propane/carb cleanered too look for vacuum leaks. It would run fine for a bit then develop an intermittent lope during idle, no cel though. Yesterday after 2 days of a 100+ mile round trips it threw a p0172 for too rich..... at this point I'm starting to suspect the diaphragm thing subaru uses as a fuel pressure regulation or the return line solenoid but honestly I'm stumped and looking for an outside, non frustrated opinion. Thanks in advance

 

[Ecmbuster]

You're likely using an OBD II tool to access the recorded faults.
If the fuel pressure regulator has a vacuum line attached, run the engine and look at the port to see if fuel is leaking out. Be aware if there is a fuel leak, attach a hose and save any leakage into a container to prevent a fire.
Use the attachment for a more interesting set of tools to access the Subaru SSM protocol.
Attach a fuel pressure gauge for testing. Attach a vacuum gauge for more simple tests.
Find a service manual for relative testing rather than tossing parts at it.
Reset the throttle body but clean it first with a new paper air filter, NOT K & N.
Test for vacuum leaks.

When the ECM is Reset and all DTC's have been cleared, the ECM idle control is also cleared.
If you have SSM3 or SSM4, simply instruct the ECM to set the idle speed.
Aftermarket bi-directional scan tools should be able to adapt the throttle program.
If there is no access to a factory style scan tool, you can recreate the proper conditions for the ECM to relearn idle control and the correct RPM to maintain idle speed under load conditions.
Load conditions include:
Cooling fans ON or OFF
A/C request
Power Steering load request
Transmission load request
Any electrical load request
Procedure:
1. Ensure all power accessories ie: lighting, heater and electrical parasites are OFF.
2. Disconnect the battery negative for 30 minutes.
3. Reconnect the battery negative.
4. Following all steps without touching any switches or pedals. Use the ignition key only.
5. Insert key to the ON position only for 20 seconds.
6a. Turn the key so that the engine starts.
6b. Set timer for 20 minutes.
6c. Let engine idle for 20 minutes.
7. Turn key OFF and leave the key in ignition for 20 seconds.
8. Remove the key.
9. Repeat step 5 and Continue to step 10a when complete.
10a. Turn the key so the engine starts and set timer for 10 minutes.
10b. Let engine idle for 10 minutes.
11. Turn the key OFF and leave key in ignition for 20 seconds.
12. Remove the key. The ECM has relearned idle speed.

Reset the clock, radio stations and electric window one-trip features.
At times, the memory electric seats and remote fobs may not operate and require a reset..