BMW Repair: 92 bmw lights, communication bus, e36 325i

Question
my headlights, tailights and interior lights flicker on my e36 325i, only when the engine is running. my engine also idles rough, my computer sends code 54. anyways everyone said voltage regulator. I know this is not the problem because i have replaced my alternator, battery and engine chassis ground and still same problem. please any ideas will be greatly appreciated!  

Answer
Well, according to my book of codes, code 54 has two different results.  1- HO2S Heater Resistance (Bank 1 Sensor 2)  and the other one is Vehicle Communication Bus C (-) shorted to Bus C (+)  So check for cross or grounded out wires.  Hope this helps..Let me know..
Rahim..