Sounds to me like the gauge is going out. With all the capacitors, and resistors, and diodes on the PCB inside the gauge, if any of them go bad, that can cause the computer to get all type of bad readings, thinking the machine is doing stuff it if not. I recently had to replace my gauge on my 05 500HO. Heavy rain storm put water in the gauge and it never worked correctly since.
First thing I would do is pop the gauge out of the pod. Spray the plugs with electrical cleaner. after they dry, plug the gauge back in making sure both plugs click firmly into place and test it again.