Determined that the low power issue was in fact the driver side rear brake was locked up due to a stuck parking brake actuator. While I was in there I rebuilt the rear brakes on both sides and bled new brake fluid.
Now, when I try to crank the engine it won't turn over enough to start. Batteries are holding 12.35v, turn the key switch on it drops to 12.28v-12.3v, but turn it all the way to start and it drops below 4v. Up until just a few weeks ago when I started it last it cranked right up.
Thoughts?