Cummins X15 starts and then dies

Just posting here in case anyone has some ideas because apparently the Cummins technicians at the shop I'm at don't have a clue after 5 hours of troubleshooting.

For the past couple months the truck has been running badly after start up occasionally. I will start it up and my rpms will not stay steady instead fluctuating up and down with the fuel pedal not providing any input. This would happen once every 2 weeks and resolve itself after shutting truck down for a bit and restarting. This last week though the frequency of this issue happening was increasing to every other day until yesterday when it finally totally stopped running. It starts fine but then stalls out.

Theres no active codes for the engine but prior inactive codes for VGT actuator prompted them to inspect that first and found it functional along with the Turbo itself. Now they sound defeated and at a loss of leads to pursue which I found odd since this is an official Cummins sale and service where all they do is Cummings so you'd think they know these engines inside and out.

I'll include some videos I took the other day of how the truck was running when I realized it was not going to resolve itself this time and needed a tow.

 

I'm unable to upload even a 5 second video clip does someone that frequents the site more often than me know how I could include videos here?

 

Thank you for that suggestion! Did you have any codes to indicate that?

 

heres a link to a video clip I uploaded to youtube and also 2 other video links to google photos.
Shared album – josiah harder - Google Photos
Shared album – josiah harder - Google Photos

The first video with my dash illuminated and the check engine warning on the screen is the oldest of the 3 videos and you can see how even though it was running strange and not allowing my cruise control to be set higher than 800 rpm it was still running better than it is in the other videos taken yesterday. I drove 900km in between those events too with no issues.

Also in the Youtube video you can notice the rpms coming up and down. Thats not me pressing the pedal thats happening on its own and characteristic of how the issue first presented itself a couple months ago but now it stalls and drops rpms immediately after start up

 

Thank you very much for those suggestions I'm going to run it by the guys there and will also update when they figured it out!

 

Truck started up after sitting in the shop all night. Nothing was done to repair it and I doubt it was gelled up cus the day I was towed it was above zero and I have winter fuel yet. Starting to think it was the secondary fuel filter as they said it doesnt look great even though only 13,000 km on it. Will be replacing that preemptively

 

I'm not sure what a Davco is so I probably don't have that. Im going to start draining the water separator more regularly. I thought if I couldnt see any water in it that it would be fine but maybe not especially in cold weather