This is a quick guide that assumes a stock 1996-2003 3800 throttle body.
"IAT" – Intake Air Temperature – This sensor is in charge of detecting the temperature of the air coming into the engine. You will find this sensor plugged into the stock rubber duct that connects your air box to your throttle body. This is a 2 wire connection.
"IAC" – Idle Air Control – This sensor is in charge of metering a small amount of airflow into the engine to keep it idling. Basically, it acts like a tiny throttle blade. You will find this sensor located on the side of the throttle body, it is a 4 wire connection.
"MAF" – Mass Air Flow – This sensor is in charge of detecting the amount of air flowing into the motor. It is located in the top outer end of the throttle body. It is identified as a rectangular black plastic box on the top of the throttle body. It is a 3 wire connection.
"TPS" – Throttle Position Sensor – This sensor is in charge of detecting the throttle blade position. It is located on the side of the throttle body and is a 3 wire connection.