In the past week my car has developed a flicker evident in all the lamps when the car is at idle this includes headlamps, taillamps, dome lamp, and dash lamps. The flickering is rhythmic and only occurs when the engine RPM is under 1200. If the car is keyed to either position there is no flickering. The first step in my diagnoses was to take the car to local advance auto parts and have the systems tested as I felt the battery was old enough to be replaced. The test results are as follows:

Battery-
Voltage 13.01 V
Measured: 857 CCA (How is this possible?!)
Rated: 600 CCA
Temp: 64*

Alternator-
No Load: 14.26v
Loaded (#4 blower motor; headlamps) 13.95v

Today, I began searching for grounding issues. First I cleaned up all the fuses, then I took apart the dash and examined to make sure all plug ins were making good contact for the headlight switch and all plugs on the back of the dash cluster were clean. For kicks I thought that I would try starting the car without the dash cluster installed or connected and I had no flicker; however, when I reinstalled the dash and ensured connections were made the lamps began flickering again.

The alternator belt tension is in within tolerance and I have no reason to believe the alternator is slipping. The 3 ground locations I know of: valve cover, compressor bracket, and battery firewall are clean and in good condition.

Should I look into replacing the voltage regulator and brushes?

or

Should I continue looking for a grounding issue? Any ideas of where the ground is not making contact on the dash?