Need Help With Vehicle Configuration

I'm seeking help with a vehicle configuration on the Ibishu Pessima (2000). I converted the car to RWD, the car drives fine and all, but whenever I put the car into park, it starts bugging out. the way it bugs out is the car goes into park, the rpm stays at idle, and the rear starts spinning over 200mph and destroys pretty much the whole rear of the car including the fuel tank. After about an hour of trying to diagnose the problem, I found that this car won't bug out (or bug out less) the smaller the wheel size you go. Looking to see if anyone can help fix this problem without having to change the wheel size. I will leave the configuration at the bottom if anyone wants to help or just experience it for themselves.


Ibishu Pessima Configurations
18 Inch Wheels (no matter which ones they were)
6-speed Automatic Gearbox
2.7 V6
Converted to RWD.

 

Have you tried to reduce the wheelbase on both axles?
Have you tried to fit smaller tires?
Try these steps.

 

I've tried all of those steps. The tires/wheels are the problem. I put smaller wheels on the car and the car starts to look silly. I've come to just give up because obviously its a bug that'll need to be fixed.

 

You do not need to change the wheels, just change the tire setting to a smaller one