Audi just shuts off no warning while driving and won't

[TWFAUST at aol.com]

I am not sure whether I read your note correctly. When the "tachometer  
drops to zero", is the motor still running? I realize that a '90 100 has a  
distributor, but for what it is worth, the ignition module on my car is 
failing.  As part of the ongoing failure, the car will drop a few cylinders and the 
 "tachometer will fall to zero". I think my suggestion is that you 
investigate  the electronics before they get to the tachometer sender/pick up.
 
I am puzzled by trouble with the temperature gauge. Are there any other  
electrical anomalies? Could there be a common source?
 
Tom Faust