2003 Hyundai Tiburon Sensor Problem

The only thing that makes sense is your first sentence. How they led you to all those unrelated things is a mystery. The intake air temperature sensor circuit is really basic and easy to diagnose. Also, the sensor has just one simple component inside so failure is extremely rare unless it has been handled roughly. Almost all problems that cause a high voltage reading are caused by a broken wire or a loose or corroded connector.

Use a digital voltmeter to read the sensor's voltage. Back-probe through the rubber seal where the wires go in. The readings have to be taken with the connector plugged in to be accurate. You'll find about 0.2 volts on the ground wire. The signal wire must have between 0.5 and 4.5 volts. Typically you'll find around 2.4 - 3.0 volts. If you find 5.0 volts, that is what will set the fault code you have. Check the connector terminals for corrosion and tightness.