Water got in Engine Air Filter Box - Anyone else have this problem?

I'm having issues with my battery charging alternating between 100% and 20% every number of seconds as I cruise along and even while I'm coasting and braking. The power drops off too, especially at low speed (when the battery would be the sole source of power to the wheels).

Going to try cleaning the MAF tomorrow on the off chance it helps, though I have a suspicion my issue is a bit more complicated.

 

Either one of the ECUs is "confused" or the HV battery is near the end of its life. Try disconnecting the 12V for a few minutes to reset the ECUs. Also check health of 12V battery. Good luck!