my '85 190e mysteriously died twice today.....

both times in the middle of traffic.
the first time i coasted into an empty parking lot and tried restarting the car. It started fine but my aftermarket stereo system did not come on which i later discovered was due to a loose ground.
the second time the car refused to start for a good 15 minutes. The fuel gauge jumped around alot while the oil pressure gauge would rise to just below the 1 bar. i had my foot on the gas while i had the key twisted all the way to the right. Does anyone know what would cause this?
thanks
doug