untethered

Agreed. Not doubting that there are vehicles that can benefit from this, but it seems the 8f35 is just a rough transmission plain and simple. Since it was developed with GM, I wonder if any of the sister transmissions to the 8f35 have issues like this too.

Are you having the symptoms the diag post mentioned like being unable to hold a steady 1500rpm in neutral? It seems like this fix hinges on the engine being unable to manage itself with fluttering. If the engine is completely smooth and fine when disconnected from the transmission, I can’t imagine this would fix that.

Or the good old leave it in a bad part of town unlocked with the keys in it (do not do this)