50% of the time is runs perfect. 50% of the time it won't stay running at idle and misfires at part throttle. It might run perfect for half the day and between stop lights start running poorly. Always runs perfect under acceleration. Mostly runs perfect when cold. Runs worse late in the day, compared to early morning.
This is a high mileage van if that makes a difference. 410K
Sent it to a good indy shop with a EGR high flow code and a #6 misfire. IAC and DPFE sensor were replaced. It ran perfect for 3 days.
Now it's back to shutting down at idle, stumbling at just off idle. No codes showing, CEL is off. The shop had it for 4 days and said they couldn't duplicate the problem. I got it back yesterday, and it's doing the same thing.
The shop is a quality shop and used to dealing with vans. They do all of the comcast and DTV vans as well as a bunch of other companies. They know vans and they are stumped.
Ideas?
Would a Ford dealer have any better luck diagnosing it, or are they going to be looking for codes as well.
wae
HalfDork
9/9/15 2:12 p.m.
A couple years back, I took my '06 E-150 to the dealer for a misfire issue that they resolved via ECU firmware update. That's the only thing that I could think of that a dealer would be better suited to discovering than a good indie shop.
What year?
It almost sounds like a dying O2 sensor. Which may not yet throw a code, depending on the era when the van was made.
that's new enough to detect O2 sensor problems... hmm
Any chance you can borrow a code reader that shows data real time? Maybe with one of those, you can see specific problems.
It could be an EGR valve that isn't always closing properly. If you can get it to run bad, shut it off, and have it still run bad when you start it after its cooled off, put your finger on the base of the EGR after a couple of minutes. If you squeal and your fingertip smokes, its probably sticking open.
Are those plug on coil? Had similar symptoms from bad plug wires arcing off to the block that came and went with some voodoo combo of atmos conditions.
alfadriver, I'll have to dig out my code reader.
Streetwise, wouldn't it throw a code for a sticking EGR and more importantly, wouldn't the shop catch that?
ultraclyde, it has a coil pack, not cop.
I'm tempted to write it off as old, worn out van and trade it in. It's not like I haven't gotten my money out of it.
I hate working on work vans. Don't they know they are suppose to run forever and never cost me a dime. 
Toyman01 wrote:
Streetwise, wouldn't it throw a code for a sticking EGR and more importantly, wouldn't the shop catch that?
Not if it doesn't have a position sensor. Ford is sometimes very bad at setting codes that actually mean anything. I've had Fords in the shop that are quite obviously dead on two cylinders, but they won't set a misfire code.
As for the shop, if it never misbehaved for them, it wouldn't be very easy to catch. Its just one of many possibilities. I've seen it fairly often, though, on all makes of cars.
And easy way to check if EGR is the problem- disconnect the solenoid (either the air or electric actuator).
It will throw that code, but you know that already. And if the misfire stays away, then it's a good chance that streetwise's suggestion is spot on.
In reply to alfadriver:
Well, unplugging the egr didn't change anything or trigger a code.
Another 30 miles and it set a low flow EGR. Still running like crap.
In reply to Toyman01:
So unless the EGR system leaks, that's not it.
(do note, the EGR system CAN leak. heck the valve may be broken and leaking off the seat)
I'm still thinking ignition. The truck I had the issue on was a coil pack '97 302. Drove me nuts trying to find the issue, and I know vans are hard on stuff like wires because of the heat containment issues. Same truck also had recurring issues on the same two EGR sensors you did, but that's probably just coincidence or standard failures.
Another 30 miles and its been running perfectly.
I hate issues like this.
It could be bad wires or connectors, look for cracked or damaged wires.
jimbbski wrote:
It could be bad wires or connectors, look for cracked or damaged wires.
That thought crossed my mind. 
There is nothing obvious and that's something that could take forever to track down. Not something I have time for.
Ford 4.6 and 5.4 misbehave if a plug or wire is bad, I know nothing about the 4.2 but it would be worth checking them
130 miles so far today and running perfectly. Too bad there was puddle of gear lube under the passenger rear tire this morning.
This thing is getting closer to the scrap heap.
Round trip today so far is at 225 miles. No stumbling, no stalls. The only thing changed is the EGR is still unplugged. I'm thinking it was stuck open and took a while to vibrate shut. I'm going to change it this weekend.
