'05 Focus with stumble/miss, no codes

[ZR]

Start there.

[2DXTRM]

Dirty TB or IAC?

[toofast306]

Update: cleaned IAC, problem prsisted. Apparently the EGRs on the Duratecs are notorious for causing problems without throwing codes. I just pulled it off this AM (damn thing is hidden by a coolant distribution block which is hidden behind the battery). I cleaned it, but it doesn't look too dirty. Not sure if I will reinstall or buy a new one ($140 for a whitebox unit!!!!).
If this doesn't fix the stumble, I will look at the PCV and hose (which is buried under the intake and may necessitate removal of the rad)...

[toofast306]

Installed the whitebox EGR and no difference - slight stumble at idle after warm-up, slight hesitation upon accelerating from a stop, down on power when cruising.
I now suspect the PCV valve and hose.
Still no codes although the traction control light is on and I can't turn it off.

[ZR]

I'd back up and have the car scanned for the Traction control code. Sure your not feeling traction control cutting in n out cutting power?

[Frankie]

Those cars are notorious for wheel bearing problems.
Bad bearing throws a trac lock code.
Maybe the cat is plugged?

[toofast306]

ZR - it doesn't feel like traction control is engaged, but hard to say for sure as I've never experienced TC activate while driving 30 km/h on flat, dry pavement. I will scan, but there is no CEL light, just the TC light.

Frankie - no indication that a wheel bearing is faulty - car coasts fine with no howling/growling. TC light appeared after R&R of battery. Cat is the original unit (187,000 kms), although the intermittent nature of the problem, commonly at low rate of acceleration, suggests it is fuel/vacuum related.

[toofast306]

OK, after looking at it with fresh eyes (and reconnecting the TPS - DUHHH!) she fires up and seems to run perfectly, but it has fooled me before.
I'll keep tabs on performance and mileage and hope that it throws a code if/when a problem arises.
Current opinion is the EGR was sticking and causing a stumble.

[Laffs]

EGR was culprit of bad shudder on my GF's

It returned many kms later and was a failing fuel pump. Ended up doing full tune up, wires, plugs, coil, filters, etc and it runs like a champ now.

[toofast306]

Looks like the PCV hose split and created a vacuum leak.
Glad I did the ignition and EGR, but this is definitely the cause of the stumble.
Intake needs to come off and I plan to install a catch can and remote PCV valve. Total PITA.
Can anybody recommend a good catch can with 5/8 barbed inlet, drain cock, and provision for a 1/2" grommet? Looks like I'm doing the soup can mod again.