CIS-E problem VW related

[IraT@aol.com]

I'm sorry to post this to the quattro list but I know many Audis and 
Volkswagens use the CIS-E engine/fuel management.  So here goes. My brother 
has an '88 16v Scirocco CIS-E and is having problems with what sounds like 
some type of ignition problem.  My brother is in Dallas and I'm in north 
eastern Tennessee so its kinda hard for me to diagnose the problem. He has 
replaced the coil (Bosch) plug wires, O2 sensor and checked for loose wires 
vacuum leaks, etc.  Each new part has helped the car but the problem still 
persists.  This what my brother says about the problem 

"it is directly related to the tachometer, because whenever it starts and 
runs bad the tach will hang on either 2,000 and stay, or it will hang on 
8,000 and not move while the motor is running.  I have to kill the engine and 
then restart it until it runs ok, it only does it on start up though, it 
won't do it any time it's running ok.  It still backfires through the pipe, 
and misfires, when it acts up, so I don't know what the heck it is"

If anyone could shed some light on this problem please let me know.

Thank you,
Ira T