I did have a thought. The power seats COULD be related to this, IF the entire issue is a shorted cell in the battery or something similar.

Go out to the car, pop hood.

Grab a multimeter and measure the voltage across the battery. Record the reading. (SHould be 12.2 to 12.5 volts)
STart engine.
Repeat the measurement. Record the reading. (Should be 13.5 to 14.2 volts)

Post both readings here.