i just bought a 96 eclipse rs with a 420a and need some advice.

i bought it knowing it had a problem, so the car idles great shifts great and i know there is no mechanical problems with the car, but as soon as the car gets to normal opperating temperature (half way on the temp gauge) it just shuts off. i got a P1391 code running a diagnostic, which i've read means either manufacturer controlled ignition system or misfire or a bad cam or crank sensor. i also read it could mabee be a ASD, so anyone that could help me out it would be greatly appreciated. thanks again.