2010 LS3 6.2L starts stumbling for 10 sec then dies.

[5557nut]

This has been a trip!
New harness, ecm, NB o2's plugs Has Innovate WB O2's also.
Had several codes but all cleared but P0315, 0204, 0621.
Can't do crank relearn on the new ecm because it will not run more than 10 sec stumbling.
Put the old ecm back in and get same codes except NO P0315.
One week ago (orig ecm) had it running like a beast. Parked then the next day went to start it...runs stumbling for 10 sec n dies. So bought a new ecm.
I don't have a clue where to look next!
Here's my tune and the last log I made when running good (orig ecm). It's only a little over 12 min but I'll post it.
Hope someone has an idea

[joecar]

Fuel rail pressure?
Injectors leaking?
Spark plugs firing?
ECM ground connections?

Did anything change between good start and failed start?

[5557nut]

Sorry for the late response. I thought I would get a notification when someone responds.
Fuel rail pressure? 58psi / 400kpa
Injectors leaking? replaced
Spark plugs firing? no misfires
ECM ground connections? new PSI harness and triple checked - they connect all grounds to one ring and I haven verified back to ecm connector.

It ended up being a Current Performance coil harness that was wired backwards...had to swap side and flip connector to the front.
Luckily there was enough length so no worries

I'm running mafless and had to revert to an original tune and start over.
I've turn off the DTC for MAF and LTFT and so far letting the O2's manage fuel which is working ok.
biggest issue is timing, after 2000rpm it has a 1 degree kr and shots to 44-45 degrees. Initial starts at 9-10.5 during idle.
I am weak at determining what to adjust to bring that down...doing a lot of reading.

Thanks for taking the time to ask