Idles very rough below 2000 RPMS. Have replaced the o2 Sensor, but the engine will not start with it connected. When disconnected, it runs great above the 2000 RPM mark up to 100 MPH or more, Was still running strong.

Back at 2000 begins to idle rough and engine will die around 500 after surging for a minute or two.

Is there a sensor that controls the idle? Could it be the injectors?

Any help would be greatly appreciated.

Ken