2000 ford focus stalling out

ok my girlfriends 2000 ford focus 2.0 sohc with 120k miles on it was sitting in idle all of a sudden the cars idle was jumping from high to low idle, all of the gages jumped everywhere, and then stalled. car wouldnt turn over, it sounded like a dead battery but the raido and everything came on fine. no engine check light had to jump it off to get it to start, then shortly died. i had the altinator and battery tested and they are good. i charged the battery up again for about a day and it was running fine then i had it sitting in idle and again same thing. a little bit of a funny smell came from inside the car but not the engine. engine temp is fine oil pressuer is good. what is wrong with my car???????????????????????