My car recently died while traveling very slowly in traffic.  Had no juice.  Just like the alternator died and it ran out of battery. No power.  Jump started it and drove it home. Put a Subaru Reman alt on in, then it died again.  Never had a warning light. Put a new battery in it. It now runs, but runs rough, and ABS comes on and off sporadically and power steering is on and off as I tried to turn. Any ideas what else electronically could be causing this?  Thanks!

Check the output of the ALT and the connections and grounds.  Computer may need to be reset as well.

Assuming it's not something related to the serpentine belt and accessories, alt, etc. your power steering fluid could be bad. My power steering assist was mildly stiff when I got my 95'. Over the course of roughly a year, it got worse and had "dead spots" where it went from assist to no assist. Thought for certain the rack was failing, but decided to change the fluid first (it uses Dexron trans fluid which doesn't age well) and I did that twice to get remnants out of the lines/rack. Completely rejuvenated the power steering assist.

 

You need to have a voltmeter (multimeter works) on your electrical system and find out if it's charging properly or not. You could also have a slipping belt, an AC compressor locking up, etc.

+1 on the P/S pump and/or fluid.