What does an engine use if it doesnt have a throttle position s***w adjustment?

Question

mine just has a tps and iac motor hooked to ecu

Answer 1

Idle speed control motor. It is controlled by the ECU.

Answer 2

It uses the throttle position sensor, air mass sensor and ecu, along with one or more oxygen sensors in the exhaust. Based on readings from the sensors, the ecu changes the amount of fuel supplied by varying the pulse width and timing to each injector. The actual idle speed is programmed into the ECU's memory.