O2 Sensor Wire
WARNING: This page is about a different car, the 1992 Pontiac Grand Prix, 1992 Oldsmobile Cutlass Supreme, and 1992 Chevrolet Lumina. However, it is still accessible from the selected car via links, so may be relevant.
O2 sensor wire may be mispositioned and laying against exhaust manifold. Check for ground between sensor and wire connector.