About to use my X as target practice

[R.C.]

I am at the end of my rope with this BMW! Every time i fix something something else breaks. Just finished putting in a new transmission valve body filter and oil in on friday. start it up and drive it around my shop a few times and everything seemed to be working great i was happy. I go to drive it home and i make it about a half a mile from my shop and my tach and nav screen go out and then every light on the dash lights up along with trans fail safe and self level inactive. Now i'm looking for a big tree to run into! Got it back to my shop and shut it off for about 5 minutes. started checking connections and everything looked good. Battery voltage was 12.8. Started it back up with my meter on the battery. voltage dropped to around 11 and then back up to 12.8 after it was started. Hit the gas and the voltage Jumped up to 14.6 then back down to 12.5 and it did this for a few minutes. when i held the engine at around 3000 rpm it jumped up to over 16 to 17 volts and all the lights on the dash came back on. I'm thinking it a bad alternator or at least a bad regulator. I'v been reading on here all weekend and i guess ill start with a new regulator and go from there. I have 40,924 miles on this thing and it is falling apart! My list of repairs is a mile long so far. Any thing else I should look for please let me know.
thanks