My son has a 95 850 which stalled out and would not start. we put a new battery in and it ran fine and drove it home( 3 miles), but the fuel light blinks and check engine is on. when you rev it up they both go out and back on when you let off the gas.Now after 3 days of not driving it, the battery is dead again.Any ideas?

 

Sounds like it could be either alternator or voltage regulator, but I'm not an expert by any means. Is the serpentine belt on tight?