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The log looks weird as if a 2 bar map sensor is set but as far as I can see the Bin has the right map type selected so not sure what is going on there. Do you have a wide band connected? In the log the wide band is doing nothing.

Yea has a wide band and indidnt think to check map settings was a vn series 1 apnx 12 p starter map

Sorry my bad, I had the 2 bar ADX loaded for some reason. And yes in the log the wide band is pegged at 10 AFR so it grounded or not working it seems so I can't actually see the true AFRs.

But in saying that I noticed 2 things, the idle target AFRs are quite lean compared to what I am used to. 2ndly the idle vacuum is low for the cam size which suggests the tune isn't right, AFR or spark or both aren't correct. The hint came after it stalled and the target AFRs went a lot richer due to the start up AFR tables in action. As soon as this happened the vacuum increased to a more sensible value. So this suggests the idle AFRs are too lean for this cam or in general. I had a look at your tune based on APNX vs the BLCD I normally use, so I compared them. Sure enough the APNX ones are quite lean.

Attached is the 2 tables compared. Try editing that table and fill it in with the richer values from the attached pic labeled BLCD.

Hmmm ok ill try the vac dosnt change much on tune were ever i set it cam was diled in and was i degree more avance from spec

What's your idle timing at? That can help raise and stable the MAP. I'd start with a flat line in the low to mid 20's. Not sure what the sweet spot for the buicks is the the V8 like up to 28 for idle

Its at around 27 degrees atm

At all map values?

I ran mine at low 20s but I also have 10:1 comp. I found having too high idle timing can make the engine stall easy if it's loaded too quickly , eg letting the clutch out too quick.

Note sure why but my best guess is having the engine loaded and slowed down abruptly while one of the pistons are on the way up while the ignition has already started so it ends up throwing the piston back down the wrong way causing the engine to abruptly stop and reverse.

I had this issue in my old vacationer, when taking off too quick with the clutch even with a bit of throttle it would abruptly stall and throw the car backwards due to the engine reversal. Lowering the timing in the idle table and main table around idle areas seemed to eliminate the issue.