when i had the problme it was my FPS (fuel pressuer sensor) had gone bad...on 98's with return systems, they have a FPR (fuel pressure regulator).
It would stall on me at low and high RPM's.
The way to find out is if there is a strong odor of gas comming from the upper intake, or the Air Filter area...or even in general form the engine bay.
Now, it is slightly possible that your problem is related to the electrical system.
My reconmendation is to replace the battery first...drive around for a bit and see if your having problems still.
Lupe
