not meaning to thread jack here, but im like the rest of you guys and have the same issue.
It used to do it really bad, then i replaced the alternator and it was clearly flickering with the stereo, so i replaced the battery. Fixed a majority of the problem, but its still flickering.
My mechanic says its the ECU playing tricks because of my broken 02 sensors.
But I have an inkling that its the plethora of wires going to my battery.
see my svt wasnt exactly cared for when i bought it.... shes getting the love she needs now but im having to piece it back together. On that note, theres about 6 wires running to my battery, three at each terminal, and half of the wires are crudely spliced together. My thought here is that I need to fish down these wires and make sure it's all solidly connected.
Im gonna suggest that y'all do the same and just make sure your battery connections are solid and wont give you any problems at any end of the cables.