Hi all, I just picked up a '97 Thunderbird with the 3.8 V6. The car is great with one issue: When it's idling while in gear, the RPM's drop to about 550 with a deep vibration you can feel through the steering wheel. When I turn the steering wheel from side to side it gets a bit worse and the steering pump makes a whining sound as if it was low on fluid. Well, the resevoir is full, but the fluid is dark charcoal in color. Also, when I put it in neutral, the RPM's go back up to 900 and the idle is smooth. I would really appreciate any ideas on what this is, and suggestions to remedy?