Well, hard to see what you mean without some examples but... do you mean two consecutive shots in continuous shooting mode and AI servo focusing are metered differently and the second (or third etc) are soft? Is your subject static or moving?
If you mean that, then you have a problem! The metering should be ok in the scenario described above, the focus might not be if you are in high speed shooting mode. Remember each time the shutter is released the focus process starts again, but it might not have finished focusing before the shutter is released again.
On Canon 1D series bodies you can tune this behaviour to give more consistent continuous shooting (same on Nikon D300/D700/D3/D3x) but so far Canon refuse to put that function into the xxD's and definitely its not in the 30D (I have one of those!)
