Misfire Cylinder 2,3,5,6 / Lean Bank 1&2 *Help*

My wife's Z3 3.0 has been garaged for a few days while hurricane Sandy came through. Today the weather cleared up and she decided to run a few errands. During this time the car ran rough during idle to the point of almost stalling out. I assumed it was due to sitting for a few days and the cold weather.

The CEL was on, so during my test drive I stopped at a local auto store and used their code scanner. So this is what I got:

P0300 Multiple Misfire Detected
P1345 Misfire Cylinder 2 With Fuel Cut-off
P1347 Misfire Cylinder 3 With Fuel Cut-off
P1351 Misfire Cylinder 5 With Fuel Cut-off
P1353 Misfire Cylinder 6 With Fuel Cut-off
P0171 Fuel System Too Lean (Bank 1)
P0174 Fuel System Too Lean (Bank 2)

I read that the lean condition could be a leak in a vacuum line, but which vacuum line.
Any idea on how to troubleshoot the misfire?

Thanks in advance!