7875 + 5.9 + E85 + Megasquirt

What is the timeline from when it dips into the 10s until you lift? To me it seems like it’s longer than a split second. If we’re talking a matter of 3-5 seconds to me it looks like fuel needs to be removed from the VE table
That seems to be the case. I went back and looked at my previous tunes and at one point my tuner added a lot of fuel to the VE table in the areas where I'm going rich. I've been slowly removing fuel in those cells and AFR is falling into place. I've also wired my 2-step and started testing it. It still needs some tuning since I'm now getting into parts of the VE table that have never been touched but I'm able to make about 3psi on the foot brake at 2300rpm.