P0171 in the 01' SPI

[Redlineracer12]

My dad's been getting a system too lean code for quite a while now in his Focus and it's definitely getting worse. The car drives fine and dandy on the highway but when he comes up to a stop (sometimes, not always) the car will stumble pretty badly, barely idles.

Has ~80k I think and has recently replaced the fuel filter (today). Also tested fuel pressure coming out of the pump and it's 50+ psi so that should be no problem.

So for p0171:
P0171 - System to Lean (Bank 1) The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. For lean and rich DTCs:
Fuel system
Excessive fuel pressure.
Leaking/contaminated fuel injectors.
Leaking fuel pressure regulator.
Low fuel pressure or running out of fuel.
Vapor recovery system.
Induction system:
Air leaks after the MAF.
Vacuum Leaks.
PCV system.
Improperly seated engine oil dipstick.
EGR system:
Leaking gasket.
Stuck EGR valve.
Leaking diaphragm or EVR.
Base Engine:
Oil overfill.
Cam timing.
Cylinder compression.
Exhaust leaks before or near the HO2Ss.
A SHRTFT-1,2 PID value between -25% to +35% and a LONGFT-1,2 PID value between -35% to +35% is acceptable. Reading beyond these values indicate a failure.

Which means about a hundred different things good be wrong Visually inspecting the vacuum hoses I don't see anything wrong with them. Tried cleaning the MAF with no luck either. I also found a few things suggesting a DPFE/EGR problem which would make sense I guess here: http://www.focushacks.com/index.php?modid=80

Maybe the EGR is staying open and causing the car to stumble like that at idle. If anyone has had DPFE failures before I wouldn't mind hearing some of the symptoms

From here I guess I'll try and catch it while it's stumbling and disconnect and plug the EGR feed to see if the idle improves. Thanks for reading my super long post

[Redlineracer12]

double post FTL

[Deagle50ae]

sounds like the same problem I am having.
threw the same code too.

[Redlineracer12]

sounds like the same problem I am having.
threw the same code too.

Well what is the problem?

[Pappy]

It's a DPFE. I'd bet my spare change on it.

They are notorious for going out. I also think last time I had one die out (on Merrily's car) that was the same code it threw.

[focinite]

on a spi if it were a DPFE it would give a po401 or a po405 insuf flow or exsesive flow. on a for a lean code will set by a unmetered air leak( I.E intake tube, intake gasket) or a O2 thats being an untard the best way to test the EGR is take and put A SMALL AMOUNT of vaccume (via a diagnostic vac pump) at idle the car should start to stall, if not you sir need a EGR valve