Yes. I talked about it in post #10 and #12. I was able to check it when it was idling bad and it was normal. And Thanks for your interest.

 

Oops, sorry I overlooked the post.

 

UPDATE. Well I found out a few more things today. This thing is driving me nuts.
I can now recreate the problem. All I have to do is create a vacuum leak (not too small) and wait about 2 minutes. Then it goes into first closed loop with o2 fault then in a very short time goes into open loop with fault. At this time the fuel trims go into a what I think is called FMEM (failure mode effects management). They go from plus 20 or so for stft and plus 10 for ltft to about plus 3 for stft and 0 for ltft. Now if I let it idle it stays this way when I eliminate the vacuum leak. If I spray just a tiny shot of brake clean in the vacuum tee I can watch the o2 graph waveform jump up then back down and in a few seconds starts going up and down like it's supposed to and the pcm goes back into closed loop. It will also go back into closed loop if I hold the rpm up around 1500 for about 30 seconds. Just needs a little boost to get it out of FMEM. It will also stop this craziness if I turn the key off and restart right away. It gets stuck in this FMEM mode after cold start and I think it's because of a vacuum leak only when cold or only bad enough when it's cold. I've looked at all the usual suspects. I don't have a smoke machine but spray everywhere doesn't pick up the idle at all. I did spray some into the valve cover with the pcv valve out of it and got just a slight increase in rpm. That could be finding its way to the other valve cover and going in the pcv vent tube. I did find a vacuum leak at the egr vacuum regulator. When using a hand vacuum pump on the manifold port and no power to valve there's a leak but found out by reading this forum that it's supposed to leak. To me that's strange.
When it's running ok the ltfts are both between 8 and 10 making me think vacuum leak. I've been recording some pids so if anyone wants to see what they are I might have recorded the right ones. They're in a .csv file I can send or somehow post here.

 

What do you get for a vacuum reading at idle when in closed and when in open loops?

 

I'll hook up a gauge and find out.

 

When it's running bad the vacuum reads around 13.5. When I get it into closed loop and it's running good vacuum reads around 16.5.

I noticed something curious. Today, at least, after I got closed loop the ltft stayed just under 10 no matter what the stft did. Also that the injector pulse width didn't go over 3.4ms even though the stft was staying at 28 for long periods of time. It was going between 3.1 and 3.3 when the stft was staying at 28. Then when stft got down around 0 the injector pulse width only went down to between 2.8 and 3.1ms.
Shouldn't the injector pulse width go up more than that when stft is asking for more? Shouldn't the ltft go higher than that when the stft is staying at 28?
What am I not seeing? Help!

 

Way too low in both cases. The vacuum read should be 20-22 inches at idle.
Was the needle steady, bouncy, drifting, etc.?

 

Steady. Right after I first started it though I noticed it climbing slowly to almost 19. The readings stabilized to what I told you. Do you think my altitude would account for low vacuum. 3500ft. Maybe my gauge is no good I checked it against another one I have and the one I used was about 5 in higher than the other. Worn cam chain? What do you suggest? And Thanks for your continued interest.

 

No, it's still too low.
Since the vacuum reading is steady you can rule out sticking valves, misfires, or clogged catalytic converters as the problems. This brings you all the way back to a vacuum leak, possible the intake manifold gasket.

 

PRETTY MUCH SOLVED. Everything sure pointed to a vacuum leak and I just couldn't find one. So....... I decided that maybe I should try propane instead of brake clean spray. First I stuck the propane hose into the air filter intake to make sure enough propane was flowing to make a difference then... Using my scanner readings from the O2 sensors I stuck the propane hose near each injector and sure enough I could watch the O2 sensor jump from around 0.04v right up to 0.9v around a few of the injectors. Much more so when the engine was warming up. When it actually would run in closed loop not only could I watch the O2 volts rise but the short term fuel trim would drop to down around 0 %. When it went into open loop with fault it didn't effect the stft only the O2 read out. Even though it ran really good when it was warm the ltft was up past 9% indicating lean. When It was warm it would still show way high O2volts 0.9 or more when using propane around the injectors, even though the O2 sensor was switching like it should in closed loop before trying propane, and the stft would drop to around 1% or so.
I figure I'll replace the injector seals and try it again and if it still shows lean and the propane still works it must be the intake gaskets or a bad intake manifold.
I had to give the Expedition back to my sister in law. She needed it. When I get it back I'll see what works and try to remember to update this thread.
Hope this helps someone. Thanks to anyone who helped me. I read threads here for many days trying to figure this out.

 

Well it does sound like you're narrowing in on the problem, that's good.

 

UPDATE! I finally got this Expedition back. It got worse. It did it all the time now.
I replaced the injector o rings and it didn't change anything. So..... I replaced the intake manifold gaskets and that fixed it. Hooooray!!!
Thanks for this forum and all the help.