Hey there, this sounds similar to an issue I had recently. All sorts of weird electrical issues that had the feeling of costing HEAPS of $$ to diagnose. Turns out the culprit was a dirty contact in the ignition switch. Simply removing the ignition switch, cleaning the contacts with electrical cleaner, reassembling, fixed it for me!
Hopefully this is the issue for you also!
Here's the guide I followed:
https://www.e46fanatics.com/threads/...atomy.1018686/
A quick way to confirm this may be your issue too, would be using a multimeter to probe in the fuse box and see if one bank of fuses is receiving significantly lower than 12V. This was the case for me.