Front subframe bolts loose?

[sasquatch]

Has anyone had problems with the front subframe bolts backing out a little causing the subframe to move slightly when driving? I've been chasing down some front suspension issues lately and suspect the subframe might be a little loose. If I lift one of the front tires off the ground and check movement by pulling the tire horizontally left-to-right (back and forth) I have some amount of movement due to the tie rod ends and the control arms but it sounds like either the subframe or maybe something in the driveline is moving when the tire/wheel moves back and forth. If I grab the tire on the top and bottom to check movement I get nothing. Solid as can be. What's strange is I get a up/down wobble from 0-30mph like a out of balance wheel but I had wheels and tires double checked....both OK. I can feel vibration in the steering wheel, especially when turning left or right. Wheel bearings check out OK.