Hey thanks for the quick input. A while back I did set all of those drivetrain parameters to no (built 4l80e and ford 9" so should be safe in this case) which still did not affect the SEMRET timing pull. That alone fixed that issue for you? I am working with a GMPP LSX376 engine controller, which did have some funky hidden idle rpm limits that I had to backdate the Operating System to get to work correctly, so thinking this may be another one of the GMPP controller gremlins :(
I had the same last-resort thought on using the b5157 table... really hate to do that on a customers car but sounds like it might be my only option, will just carefully explain what to be mindful of as far as detonation if they get a tank of bad fuel.