I've been driving this car for several years, but yesterday after I went to drive back home, it started having electrical issues. When it started, the tachometer went crazy, bouncing all over the place, yet the engine speed stayed constant. After driving about a mile, the inside dash lights got really dim and the headlights started fading out. Eventually it started to de-accel even though my foot was floored and it eventually died. I checked several fuses, and turned the headlights on and they were super bright as if the car were running. After getting a jump start, I drove about 1/4 mile and it did the same thing. After I turned all inside electrical stuff off and went to start it, it would struggle to revolve once. Later that night (a good 3 or 4 hours later) I stopped where it was parked and tried it once more. It fired right up with no problems.

I was thinking the alt. was going bad, but if it was, wouldn't the batt be dead?
The little battery image on my dash would randomly, lightly flicker on and off. The battery connections are tight and it's a new-ish battery.
Any ideas?
Thanks in advance!
- Matt