94' Sunbird Wiring Issues?

So heres my problem...94' sunbird, 3.1L V6 2dr. I recently replaced the alternator and the battery is in good condition. Recently I have noticed that my accessories, mainly the wipers and passenger electric window have been acting up. When my foot is on the gas, the volt meter reads almost full, however, when the car is idling it is below half. I understand it charges more the more the alternator works. In normal stop and go traffic the wipers are slow (even if on high), but when im on the highway for example, they work at their normal speed. Also, when im bombing around in normal stop and go traffic the passenger window will just stop if I try and roll it up. It is like it has no power all of a sudden. I know the motor isnt shot because if I turn off the car for a minute and turn it back on, the window will roll up fine. It has been suggested to me that I may have a wiring issue somewhere. I have checked the connection at the battery and there is no sign of corrosion and the connections are solid. Has anybody experienced similar if not the same problem? Where should I start looking, aside from the battery?

thanks for any help.
Brandon

Get yourself a volt meter (multimeter), then check the battery voltage:

With the engine off, should be about 12 volts

While cranking (starting) should not go below 9 volts

While running should be near 14 volts, and should not change much at all rpm's.

The alternator has a built in voltage regulator, this could be the problem.

The power window motor also has a built in regulator, if it heats up it will break the curcuit.
This happens more as they age, or if they are given too much voltage - like from a bad alternator voltage regulator.