2004 Impala Issue

My wife has managed to crank out 110K miles on her 2004 Impala with the 3.4L V6.  About 14 days and 2100 miles ago we got a tune up.  The tune-up consisted of replacing plugs, wires, oil, fuel filter, and a K&N Air Filter.  She complained that it ran a little louder than before and I sold her on the fact that it was just breathing better.

However she started complaining about a belt squeaking.  Just here and there for about a second or two.

Today on her commute to work, she said, "I was driving and all of a sudden it was hard to turn the wheel and i felt like i had no power to the car and then i turned onto a road and then a heard a lound skreeching again and then the battery light flashed"  The car was fine after that and she drove it back to the house.

She called me and let me have it, and she called the mechanic and let him have it.  I drove home and took the car to the mechanic.  He kind of shrugged at me with empathy, but he doesn't know how good a wife she is.

Anyway, he said a ground wire connected to the transmission was loose.  And he was going to check a couple for more things out.

I did some Google searches on it and see that the 2001-2003 high mileage Impalas had some similar issues.  

Has anybody heard of this occuring in the 2004 model?  If that ground wire was loose and the battery had drained the car would have run, but none of the electrical would have, nor would I have been able to restart the car when I got home.

Would there be a loss of power like that with the alternator?

Flywheel going bad?

Just a hicup?  

Serpentine belt tensioner?