I'm having this peculiar problem, bought this car second hand, looks great.
It runs but keeps quitting after a few minutes. While its running, if i turn headlights on or hit the horn or release the park brake, the engine stalls out. Checked voltage at battery, 12.8 v when not running, 18 volts when running, changed PCM and same thing. Anyone have any ideas as to what can cause this?

 

Sounds you have a bad ground or loose wire somewhere. Good luck.

 

18 volts sounds very high. Maybe voltage regulator?

 

holy crap... 18 volts? That will cook your pcm in no time.