Go to the library and look into the Mitchell's Manuals for the flow chart on how to diagnose this problem. It will walk you through the process using a volt/ohm meter.
Since you are getting too high voltage from your alternator, and it is presumed to be good since it has been replaced, then it has to be something in your wiring. Either the alternator thinks it needs to put out more juice (car believes there is a high electrical demand) or something is telling the voltage regulator that it is not really putting out 14 volts, so it is compensating. There's two possibilities and there are always 5.
The Mitchell's manuals have helped me fix a lot of cars. Some libraries don't carry them anymore though. Instead the have computers that will tell you which libraries have them........which is what the one in my town is like. They don't have much of what I need, but they can tell me how far I have to drive to find it, bastards.
Steve