Multiple engineer error codes on 05 AWD limited

[lan_baba]

The error codes from advance auto are: P0106, P0171, P0174 and P0401. And here is the story:
Got out of the office early this afternoon and went to pick up the kid. Everything is fine until got the kid out of the school and in the car. The car started, but the engine is shaking. OK, turn the car off, wait a few sec, started again. Still shaking. Put into drive gear, seems a little better, and when the speed pick up, much better although I can still feel a little bit vib. Before reach home, on every traffic light, when my foot on the brake, I can feel more vib. Before arriving home, the engine light on and entered the failsafe mode. Restarted the car, managed to drive home, and went to advance auto to check the code.
Before went to advance auto to check the code, searched web and seems that either throttle body or mass air flow sensor. cleaned them both, no effect. And if I disconnect the MAF, engine will idle at 900rpm instead of 750rpm, and less vib. Still in idle, give the gas, vib almost gone after 2000rpm (with and without MAF). Also, during idle, at the first minute or so, the engine is smoother than after the first minute. With ehe MAF connected, after first minute or so, the engine seems more like choking (heavy vib).
Finally went to advance auto and multi codes poped up: P0106, P0171, P0174 and P0401.
Any idea what exactly is wrong with the car?
BTW, also noticed that the Transaxle roll restrictor have the same problem as the post here: My Ford Freestyle .com • View topic - Replacing Spark Plugs / Transaxle Roll Resistor

[theoldwizard]

P0106 - Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem
P0171 - System too Lean (Bank 1)
P0174 - System too Lean (Bank 2)
P0401 - Exhaust Gas Recirculation Flow Insufficient Detected

Whenever you see P0171 and P0174 together you likely have a vacuum leak. That leak could cause the other errors and your driveability problems also.

[lan_baba]

I did some vacuum check tonight, and seems find the problem. Look at the following two pictures, I sprayed some carb cleaner onto both of them, and then a few seconds later, the engine smoothed. But it only lasted about 10 seconds, then vib again. Do you think it is the leak, one of them? I think the 2nd picture is more suspious, since the black part is already kind of wet/oily before I spray the carb cleaner. What do you think?

[theoldwizard]

Originally Posted by lan_baba

What do you think?

When carb cleaner sprayed on the outside of a running engine and it affects the operation, it is almost assuredly a sign of a vacuum leak.

[lan_baba]

Any idea what that part in the 2nd pic is called? I mean that wet/oil part. Thanks.

[Cuda_Jim]

PCV hose....the PCV is on the other end, fastened to the valve cover. It can the source of a vacuum leak.
With the engine running push it firmly downward. If the engine clears up you found your problem.