our '99 dodge stratus has almost reached 100K miles, and it's starting to have issues. here the most recent:

after starting up the car, steering is very difficult and slow to respond. in reverse, the steering wheel will briefly lock up before releasing, and going forward, the wheel shudders and jerks for a few seconds before responding. after we get going, even at low speed, there are no problems at all -- it seems to only happen right after start-up. the power steering fluid levels are fine -- although it's probably been a while since it's been flushed. there don't appear to be any leaks, and we've had the shocks/struts/wheel bearings/brakes replaced within the last 5,000-10,000 miles.

any ideas about what this might be?