'05 Focus with stumble/miss, no codes

[toofast306]

Wife's Focus has an intermittent stumble, particularly when accelerating from a stop.
New plugs and coil packs, fuel pump works fine, fair amount of pressure in crankcase at idle (suspect PCV issue and/or PCV hose is cracked).
She drove it a couple of times and it stumbled, stalled, then threw a code which I accidentally erased before I could read it (thanks Mac tool scanner).
I drove it 3 times since it cut out and it never stalled or threw a code for me, despite putting it through the paces and through heavy traffic (thanks Toronto construction).
R&R of the PCV is a b!tch 'cuz it's tucked under the intake manifold (thanks Ford)
Any suggestions before I attack the intake?

[ZR]

Did you try cleaning the MAF?
Does yours have that goofy non replaceable air filter?
Vid below shows how to remove.

[Blackmare]

This is the kit I bought to bypass the "lifetime" filter when I had my '05.

http://www.steeda.ca/ford-focus-part...atec/555-3104/

[ZR]

If it has a "lifetime" filter, good chance it's not in good shape.
Ridiculous on Fords part.

[Blackmare]

Yep, came with a lifetime air filter. Not a serviceable part.

From the Focus Fanatics site

The 05-07 Focushave a lifetime sealed filter that Ford says never needs replacement. The only way to know for sure if its done is to look at that clear sight glass located on the intake tubing that has a green section and a red section with a yellow bladder in the middle. If that yellow part moves to the red part of the sight glass then you know the filter is plugged up and needs replacement.

[ZR]

Best part about ditchin it, car will run better vs than it ever has (quote from Scott B).

[Blackmare]

Best part about ditchin it, car will run better vs than it ever has (quote from Scott B).

Yep, made a big difference in my case. Cleaning the MAF also really helped.

[toofast306]

Got a nice CAI in there now.
Only cleaned the MAF once with circuit board dust spray as I understand the slot-style MAF is sensitive to cleaners.
Would a malfunctioning MAF not throw a code?

[ZR]

We use nothing but brake cleans on em here. No idea if what you used is a good, bad or indifferent choice.
Did it run differently after cleaning?

[toofast306]

no, MAF was cleaned when the CAI was installed about 2 or 3 years ago.
I guess it's that time.