Got a check engine light during otherwise normal drive. OBDII shows P1131. No other codes incl. pending. The graph for upstream O2 and short term trim shows oscillation, then if I let it warm up and rev it a few times, upstream O2 pegs lean, near 0V, trim maxes out. Stays that way for several minutes to forever. Idling is irregular, engine is a bit jiggly at those lower RPMs. No unusual sounds. No stalls. Exhaust a little stinky. 86K miles. OBD reading: https://drive.google.com/file/d/1O3bLQAH6JuAHyNQCukuriWNDk5laGVor/view?usp=sharing Eventually the computer gives up and resets trim to 0%, engine runs better. Saw no obvious vacuum leaks though I wasn't thorough, wiggled the connectors on engine, O2 sensor, wiggled wires near what appears to be a grounding block near passenger-side fender. No dice. Sometimes the oscillation manages to kick back in but usually goes out with a rev. and may never come back. Ideas?