Intermittent Brake Issues

[pilotXC]

I looked all over the posts on brakes and didn't see anything relating to my issue so wanted to see if anyone has experienced this before...

The dummy light comes on some times and the pedal goes nearly to the floor, but the brakes work, just ok... Then they will be normal again. Yesterday this was basically every other time I stepped on the pedal, once would go to the floor, next would be normal, then back to the floor, then normal again. The light was on at first, then went off by the time I got home but the pedal kept going in and out.

I'm assuming I have a sticky wheel cylinder on one of my rear drums as the fluid is full in the master cylinder and the prop valve probably has zero influence on this particular issue if the light is turning off and on. BUT, I"m not sure and haven't dove into it, just curious if anyone has experienced this and/or has any ideas beyond this? Thanks!