99 Mercury Sable Power Failure

Ok, so I am new at this, but I really need some help.

I have a 99 Sable which has given me a bit of trouble lately. Over the summer I completely re-did the breaks, which was a pain in the neck, but now its doing this strange thing where if I am stuck in traffic, or I have many red lights, the power starts to die out. The fans will stop working for the heater, the dash will dim, the clock will dim, and the car will start making a low whine, though it doesn't stall out.

The moment I step on the accellerator, however, it picks back up until I take my foot off, so I've resorted to putting the car in neutral at long stops and revving the engine. However, if this happens and I stop the car, I end up needing a jump. A jump will let me drive normally again for awhile - especially if I take a long trip on the highway or something - it is almost as if it re-charges.

One shop tested my battery and said it was fine, and they couldn't determine any problems, so I don't know what to do. Help!

~Frustrated Sable Owner :uhoh:

Two possible culprits: Voltage Regulator or Alternator gone bad. AutoZone should be able to check your Alternator fo
-0-. Not sure about the VR though