Possible Causes

Throttle adaptions not performed after battery disconnect

TPS disconnected

TPS to ECM sense circuits open circuit, high resistance

Throttle motor power relay failure

Throttle motor power relay to ECM circuit fault

Throttle motor power relay power supply open circuit

ECM ground circuit fault (relay coil drive)

Throttle motor to ECM drive circuits open circuit, short circuit, high resistance

Throttle motor failure

Throttle assembly failure