LS2 Drivetrain in an older car

I have a 1980 Chevrolet Malibu into which I have installed an LS2 drivetrain out of a 2006 GTO. The transmission is an automatic. As we all know, there aren't nearly as many sensors on the chassis of my vehicle as there were in the 2006 GTO. For example, VATS had to be disabled just to get the engine to start. I thought I had taken care of all of these gotchas, but apparently I have not.
My latest issue is that I cannot get more than 50% throttle opening when the car is in any gear other than Park or Neutral. I'm guessing my problem has to do with the absence of traction control sensors on the chassis. So, if any of you can tell me what to do in order to enable full throttle in every gear, I would greatly appreciate it.

On the torque management page is Rpm vs Gear all set to 6000? Try turning the ETC TCS method to disabled and see if it still happens. Or disable it completely. You should also be able to log all the Torque modifiers such at traction control to see what the issue is.