Q: when i turn my steering wheel to the right--even slightly--my engine stops. why

Hi there, thanks for writing in.

I have never experienced this exact issue before. First we should address the vacuum leak, which could cause the car to stall while idling, as well as being a potential cause of the oxygen sensor fault. Usually stalling from a vacuum leak would not be affected by turning the wheel only one direction, even slightly. It also sounds like it could be a problem with the ignition switch. Perhaps there is a wiring issue to the switch, or an issue with the switch itself, and when the wheel is turned it may move a chaffed wire or loose connection in just a way that it causes the ignition to turn off. In order to properly diagnose this issue, it would need to be thoroughly inspected in person by a qualified technician, such as one available from YourMechanic.