2003 tiburon gt idles at 3000 rpms runs fine other than that only getting codes for o2 sensors replaced iac valve and tps already and no change i did have new header and exhaust installed with out cats also performace clutch but just cant find the problem. ne suggestions?

SOURCE: Code p1166 only months after New Plugs, wires, Air Filter, & OLF?

Change the air flow meter on the air intake pipe.

SOURCE: Location of the Purge Control Valve for 2003 Hyundai Tiburon

There were two different engines which were installed in the 2003 Tiberon... the 2.0 liter 4 cylinder:


And the 2.7 Liter V6:

SOURCE: 2003 hyundai tiburon check engine light

You're right, the PO154 has to do with the O2 sensor. The code has the info of Oxygen Sensor Circuit No Activity Detected (Bank 2 Sensor 1).
Bank 2 is the exhaust manifold that cylinder #2 uses.
Sensor 1 is the sensor in BETWEEN the exhaust manifold and the catalytic converter.
No Activity Detected in the circuit could mean the O2 sensor is dead, or an open/cut wire going to the sensor.
That's about all the info you can get out of that code PO154.

SOURCE: Need Instructions on 2003 Hyundai Tiburon Clutch Replacement

Go to http://www.hmaservice.com/ and register (vehicle by VIN). Afterward, you'll have access to technical information (manuals, wiring diagrams, service bulletins, etc) about your vehicle.

SOURCE: How to replace clutch on 2003 HYundai Tiburon Gt

I recommend you get the Haynes repair manual on your vehicle. It will give you illustrations and some short cuts to make lining the clutch up a lot easier.