Hey guys, I've got a vibration coming from the front end.

The car is doing it only under two conditions:
- While turning left at slow speeds (5-25mph) in reverse or drive.
- While braking in a straight line to slow from reversing.

Details about when I hear it:
- The vibration only happens with my foot off of the accelerator. Applying some accelerator stops the vibration.
- The vibration does not happen when the car is still and at idle.
- The vibration does not happen when the car is moving straight at any speed in either direction.
- The vibration does not happen when the car is moving and turning to the right.
- The vibration does not happen while turning at higher speeds while coasting or accelerating.
- The vibration is unaffected by brake application.
- The vibration does seem to get louder (not more rapid) at the top end of the speed range in which I it is happening.

Thoughts? I have done no troubleshooting so far apart from make a comprehensive list of when the car exhibits the symptom.