Disconnected O2 Sensor ...
 

I disconneted the O2 sensor to hopefully correct a surging idle situation. After disconnecting the car ran very strangely? It still surged but also bucked when starting. I wrote the bucking off to a cold engine, but after letting warm up it continued to buck and when I tried to let it unwind it would reach 4k RPM and then stutter and would not go above 4k? Reconnected the sensor and it ran fine, but the idle still surged.

Not sure I disconnected the sensor? I (think) disconnected the power to the sensor by disconnecting the power wire at the fuse block in the engine compartment ?