#2 and #3 would possibly be caused by #1, just pointing that out. O2 sensors are usually pretty simple to replace, they can be pretty tight after heating/cooling for so many years and the wires can become brittle.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth