C280 starts but won't run (usually/sometimes)

[Forrest]

My daughter's '96 C280 developed a problem overnight:

- it will start OK, but usually won't continue running
- sometimes when it is idling it will suddenly stop, just as if the ignition was turned off
- other times it will run OK

We were able to get to the gas station and fill it up yesterday, seemed to improve - but bad behavior is still there today.

When I was trying to start it today I stopped after 10 or so attempts and waited about 5 minutes. When I tried again, it started up OK with some initial fluctuation in idle speed that smoothed out in less than a minute.

Has anyone experienced a similar problem or have some ideas as to what the cause might be?

Thanks,
Forrest