Slow battery drain, procedure for checking?

Sounds like you’ve already tackled a lot of the big maintenance items—nice work. For the battery drain, the most common culprits on older Toyotas are interior lights (glovebox, dome, or door switches sticking), aftermarket stereos/alarms, or a shorted relay. Easiest way to track it down is with a multimeter: pull the negative battery cable, put the meter in series, and start pulling fuses one at a time until the draw drops. That’ll point you straight to the circuit causing the drain.