Maybe send this guy a PM to ask more about his problem and the solution:
https://www.m3post.com/forums/showthread.php?t=1509401
Or this
https://www.m3post.com/forums/showthread.php?t=772584
https://forums.m3cutters.co.uk/threa...se-help.66440/
Also, some people have said they experience detonation at low rpm in an upper gear. That would pull timing and drop power. You could try better fuel to see if it makes a difference.