Still at the mechanic. They think a faulty battery cable could be the issue instead of the alternator. They're also replacing the suspension compressor while it's there and ran into rusted/frozen bolts on the compressor cover so won't get it back until next week.

 

Quick update. They replaced the battery cable and the battery. They also replaced the air suspension compressor. I've driven about 60 miles with multiple cold starts and no stumble yet. It could just still be that the hard reset made it go away and it'll be back. They said the battery cable wasn't making good contact with the battery so it was sometimes getting full voltage and other times not. No idea how this could have caused the stumble after start other than maybe freaking out a sensor or computer, or something had a bad connection till it heated up. Will let you know if it comes back, but might be a good idea to check voltages/battery.

 

Thank you for following up with your update.
I will take a look at my cables also although these electrical gremlins are just very frustrating to diagnose.
If I find anything noteworthy, I’ll be sure to share back.
be well

 

Same issue I had with my V6, but mine was more prone to act up just after i filled the fuel tank... and no, just to the first click of the pump handle. I replaced the EGR and no more stumbling issues. I was interested that you had the same issue and remedy for your V8... but I see it didn't ultimately. I should have read all the way through the thread!