Swapping rims to drop from 18" to 17" wheels, primarily. But these also have a different backspacing that will push the wheels out a little.
Apparently the diaphragm in the pcv oil trap can become clogged/nonfunctional, messing up crankcase venting and causing the lean condition code. Everything I read pointed to this as one of the first things to do, not very expensive, and relatively simple to swap. I had no noticeable driveability issues associated with it. After the replacement, the code cleared itself after about 3-4 days of driving. It probably would have cleared sooner, but a garage took it upon themselves to clear the codes and reset the monitors before I started troubleshooting myself, so I had to wait for the O2 monitor to become ready again.
