I have 92 LS400, w/tarction control. It has many problems, power seats are not working (relays are making littele sound), mirrors are moving only to up and down, seat heaters not working left front speaker is making cracking sound, and battary is getting empty all the time, speedomeeeter too is dead along with halfded fuel meter. But this is ok if I get the right diagrams and key to read them. Today, half of my cylinders stopped working. Engine started to stall and to smell like unburned or leaking fuel. After stopping (first I was shure that my fuel is ending but after stopping at the gas station and noticeing some smoke I think its not ok.
You could have a loose wire connection somewhere and is going to take some testings and diagnostics to get to the problem. Try checking wire harness connectors at junction/fuse boxes for a start.
Firstly you would need a DVOM or testlight and start with power supply to any one component that is not working first.
As to mirror not working correctly, that could be a fault with the switch.