Crazy electrical problems.

[zoidberg444]

I had some odd electrical gremlins when my alternator went bad - not as bad as yours but it was quite obvious the electrical system was experiencing a voltage drop. My voltage regulator was on the way out. This manifested in lights dimming and the engine acting strangely. I have seen plenty of videos on YouTube of mechanics in the US complaining most of the re-man parts like alternators and starters sold by the autoparts store are basically junk. I would probably find a genuine Toyota one from a scrapyard or order the Denso brand replacement.

If its not that - something this weird will probably be a ground issue or some wires shorted together somewhere - I would probably start looking through the wiring diagrams trying to find what they all have in common. These sorts of issues really are a pig to fix and you will probably end up having to have a professional diagnose it.