P0401, 0171 & 0174; engine stalls at the light

I have a '98 Ford Taurus with the V6 Duratec motor. I'm getting fault coes P0401, P0171 & P0174 and it will often stop very suddenly while sitting at the stop light. I have fixed several vacuum lines but the problem persists. Thanks for your suggestions.

The P0401 probably has nothing to do with the stalling. This is the DOHC motor correct? The DPFE and or the egr passages are clogged causing that code. As far as the stalling and the P0171 and 174 the pcv hose elbow is usually the cause of this. It is very hard to see under the throttle body. Also the intake seals do leak the upper and lower. But this usually causes it to run rough only when cold. Carefully you can get some carb. cleaner and spray around the intake and around the throttle body and see if the idle changes and thats is where your leak is.
If it is bad enough to make it stall it should be easy to find.

Blue bull, is your idle steady, if not just tap on top of the IAC valve and see if you
get a better idle, these often stick due to carbon build up.
you can sometimes get away with just cleaning out the carbon buildup.
just an idea

ascent and greggarage, thanks for the reply. It is the DOHC engine. I did spray around the intake manifold and all seems tight. I will check the pcv hose elbow, however the engine usually runs smooth and just cuts out. One thing I noticed is the rpm can remain high and takes time to slow down to idle, even when it's warmed up. Perhaps the IAC valve is sticky. Thanks - I'll check back.

The iac will not cause the two lean codes, a vacuum leak or a sticking iac valve could cause the idle to what its doing.

Hey ascemt - thanks for your help. I had a hard time finding the car available to work on and an even harder time locating the PCV hose under the throttle body. It had a fairly large hole in it and once replaced, the engine no longer stalls. Great suggestions!