E67 Will Not Obey Commanded Idle! (files attached)

*EDIT* Changed title once I realized what was going on. The tune/OS 12638778 in the GMPP E67 controllers have a known issue of not being able to get the idle rpm to go below 875, regardless of ANY of the parameters we have access to (EFI live nor HPT) I found a couple threads of work-arounds on HPT forum but wondering if anyone here with EFI Live has successfully solved this problem? Is there an earlier version of 12638778 out there that does not have this mystery idle rpm limit?

hopefully these reference links are ok...
Post #9 in this first one sounds promising: https://forum.hptuners.com/showthrea...igh-Idle-Issue
https://forum.hptuners.com/showthrea...e-stuck-850rpm
https://forum.hptuners.com/showthrea...-ls3-high-idle

Original post:

Working on a customers LSX376-525 with 2.9l Whipple and something is preventing the throttle blade from trying to close to drop idle speed to the commanded value. Timing is not being pulled to try to help either (real-time values are matching B5104 base idle spark table). It either doesn't know its 100+rpm too high, or it just doesn't care lol.
I suspected B1829 Minimum Idle Airflow, but cutting the values around the idle range in half didn't change anything. Any idea what I am missing? Thanks!
Log and tune files:
Attachment 23633
Attachment 23634

OK, so.... potential solution! Start with tune file "2010 GMPP E-ROD" (12638778) and update all values/tables with your tune file parameters "RevS idle Checkpoint" (12638778) in my case, and viola; no more hidden idle RPM minimum limit!!!
Now, only two small details I'm not familiar with... How does one go about transferring all the values from one .tun file to another of the same OS? Surely there has to be some way other than manually copying and pasting thousands of values?!? Secondly, after renaming that updated "2010 GMPP E-ROD" file something like "RevT idle min fixed" would there be any issue with writing this into the PCM? Standard re-flash or "full" flash?
Never thought lowering the idle 100rpm was going to be the most difficult part of this tuning job :help:

Attachment 23641
Attachment 23638
Attachment 23639
Attachment 23640

Update, so I did confirm that the work-around did in fact work! would really be nice to simply be able to see that hidden idle rpm value/table in the lsx376-480/525 tune files, but in the meantime, if anyone else is running into this issue:
1) Open the 2010 GMPP E-Rod tune file (attached to my post above or download from tune file depot)
2) Load comparison file (your tune file you want to run, with same 12638778 os of course)
3) Edit > Create Script , name it, and save
4) Edit > Run Script, open it, and run
5) Transfer your VIN over (copy and paste it into the VIN field in the "calibration" window
6) "Program PCM with currently loaded calibration"