Couple questons (91 Euro)

(I hate php boards...always losing posts! Well, they say third times, the charm{g})
Couple of quick questions:
91 Lumina Euro 2door 3.1

1. Power steering seems to be failing. Makes a humming/grinding noise when turning and don't feel much assist in steering. Mechanic can't find any leaks, pump and rack seem to be fine.

2. Every once in a while, I'll be at a stop sign/light and the car will rev to 800RPM (from the normal 500 idle) and then drop like a rock and stall. Restarts almost instantly. Done a tuneup. A friend in the industry told me to have the "Torque Converter Lock" checked. As this is the first car I've ever owned with overdrive I'm at a loss, does this make sense to anyone? Car does seem to rev higher before shifting into the next gear on acceleration.

Any help would be appreciated.

Thanks,