you sure the engine was warm?
in neutral your motor is limited to 7100 rpms. when the motor is cold it has this same limit at 7100 rpms.
If this happened when you tried to launch the car you can hit that same 7100 rpms limiter. when the wheels spin too much the engine thinks it's free reving and instates the neutral rev limiter.
vacuum problem sounds like maybe you installed an Intake and didnt connect one of the hoses correctly?
Agreed. Scared the shit out of me one night when I went to hit lift and I couldn't go past like 6.5k RPM.
Then I looked at the temperature needle.
If your lift bolts were broken, your powerband wouldn't end at 7k.
A: Have a GT that is badged as a GTS. Take a picture of the engine bay to be sure.
B: Your car isn't "warm." Wait until the car is fully warm to use lift.