First off, I am pretty good with 7.3's but this one has me stumped! Just started a week or so ago. It has been parked since then. Starts up runs fine for a little bit but then starts to shake and will not run very good. If you shut it off, then restart, it runs fine. Sometimes for a couple days. Then repeats itself. I tried pulling codes on my STC tuner code reader. It is my sons, but no codes. Well it had a trans code that I had fixed but not cleared and wastegate code that I also fixed. It was having a longer then normal crank to start for a while but that went away when I changed the IDM. I have had the 140 volt one for a couple years so I put it in. Now that was done after I started having this problem, so it isn't that. It seems to have good fuel pressure and runs really good on higher RPM's, just happens at lower slow driving. At least that is when I have noticed it. Normal things have been checked, oil etc., so it has me fooled.
Chet
Also I have a apple phone so I have been told the forscan don't work well with that phone.

 

Seems to have good fuel pressure or it does have good fuel pressure? We can never assume anything let alone on a truck in it's 20's. I'd check for aeration in the fuel also. The fact you're not getting any codes suggests it's fuel related.

 

How’s the ATF level? If this happens when stopped in gear then the TC could be going into lockup. Mark has said this can happen with low fluid levels.

Besides that I would check fuel pressure as udsuth mentioned and then try to log some data with FORScan. Even if it’s not the best with the iPhone it’s better than no data.

 

I'm thinking fuel too. How's the in-tank pickup and fuel level?

 

I thought fuel as well but there is no aeration of fuel and it is clean and seems to have good pressure. I've gone threw this years back when some buddy in Vegas dumped something in my fuel tank and I went threw three pumps before I dropped the tank and repaired everything. It is 3/4 tank, and I have done all the mods years back. I will check trans again, but when I checked it last time it was full, and know leaks. That's why I am so stumped! And it runs at higher speeds with know problem. Would sound like torq convertor but it does not feel like that also. Keep coming up with idea's , I am an office at the American Legion and have to go down there, something to do with the wheel chair program. I really need to get on this.
Thank you every buddy for these comments, every little bit helps! I will have to make a fuel pressure gauge . I need some new gauges so I will buy one as well. Like to tow my fifth wheel soon!

 

I remember reading a thread a year or 2 back that seemed to have similar symptoms. Can't remember who it was though, @Sous would likely know. Anyway they were able to track it to a failing oil temperature sensor. It was sending bad readings causing the PCM to react to a problem that wasn't there.

 

Maybe it was @ArmyLifer ?

I recall the thread you are referring to, but my brain is failing me at the moment.

 

Hopefully Armylifer can join in!

 

Chet, I believe the link below is to his thread surrounding the surge and stalling issue.

Link: https://www.ford-trucks.com/forums/1...excursion.html

 

Joining in! I just reviewed my Excursion stalls and surges thread because I couldn't remember the exact solution. Originally I thought it was ICP. Replaced it and it's pigtail all was well for a few weeks, then the issue returned. Did a lot of graphing and others helping me with analysis. Tried another new OEM ICP, better for a while before the issue returned. Final "solution" was another new ICP pigtail with a quality crimper, and noticed that the oil temp sensor plug clip was broken and loose, so I zip-tied those connectors together. That all seemed to do the trick. Don't know which part actually solved the issue.

Another data point not in that thread is my alternator started failing shortly after all this and gave me some transmission issues. The voltage fluctuation could have caused issues with the ICP too possibly?

Been running like a top for the almost two years since then...knock on wood.

 

Just read threw this hole thread. It is worth checking out. It is in the HPOP reservoir I would think. Never paid it much attention before.
I will see what I find.

 

All this EOT talk reminded me of when I had a wire break at the connector. The truck would mostly run fine at speed but while coasting to a stop it would start stumbling and surging almost trying to die. Take off from the stop and it would pick up, clear it's throat and run fine again. Hope that ends up being the trouble. Cheap simple fixes are my favorite. I may be seeing a correlation w/ the women I date. Hmmm?

 

I have never had "easy fix" whatsoever.

Chet,hoping easy fix for you in this one!

How's that SCT for pulling codes??
Maybe try with ForScan (with compatible equipment) or ancient AE.

 

The SCT pulled three codes, not hard at all. One trans code and two waste gate codes. I have fixed both of them, but know other codes present.
My son got PHP tuning for his 6.0 a while back. That is were I got it form. As far as ForScan, I have been told it don't work well with Apple phones. And I don't have a lap top so haven't tried it. It's been really hot here is Norco, California so I haven't looked at it yet. Between my wife and the legion, I haven't had much time. Been spraying for weeds here and my old body isn't what it use to be. About kills me. But it has to be done. Next season, I will pay to have all this done. Hopefully by Friday I will have an answer for all you guys.

 

Chet, I don't know SCT at all, but I seem to recall TorquePro only pulling some codes and leaving some a mystery. Perhaps this is what SCT is doing?

As for FORScan, I am 90% certain it is on the Apple App Store now and has been for a couple years. FORScan is by far the cheapest and best method to see what the PCM is seeing.

Getting old sucks...