Power Steering causes crazy idle!?!

Hey guys, just wanted to see if anyone could diagnose this. The shop I took the car to said they have worked on a lot of Honda's but have never seen this problem:

When the car is running, and stopped (in neutral, I have a 5spd), and I turn the steering wheel either direction it causes the idle to go up and down irratically. It also makes a loud huming noise. As soon as I stop turning the wheel, the idle goes back to normal. When I am driving I don't notice anything like this.

Has anyone else experienced this with their early 90s Accords? Thanks!