The throttle body might be bad or dirty. You can try to clean it and then do a Throttle Valve Relearn and Idle Air Volume Relearn
Throttle Valve Relearn
Throttle Valve Closed Postion Learning is to learn the fully closed postion of the throttle valve by monitoring the throttle position sensor output signal. It must be performed each time harness of
electric throttle control actuator or ECM is disconnect.
1.Make sure accelerator pedal is fully released.
2. Turn ignition ON
3. Turn igntion switch OFF and wait at least 10 seconds. Make sure that the throttle valve moves during the 10 seconds by confrming the operating sound.
(You can hear the TB sound when you have key on and shifter in first gear and step on the gas. So you know what you listening for.)
Idle Air Volume Relearn Procedure
The Following Condtions Must be met in order for procedure to Work.
Battery Voltage :More than 12.9 volts at idle
Engine Coolant Temp 158-203 degrees Farenhiet
Electric Load Switch OFF i.e Air Condition, headlamps , rear defogger
Steering Wheel: Neutral Postion (Straight Ahead)
PNP Switch: OFF (Park Neutral Switch i.e. Clutch Switch...pretty sure)
1. Perform ACCERLEARATOR PEDAL RELEASED POSTIONS LEARNING
2. Perform THROTTLE VALVE CLOSED POSITION LEARNING
3. Start engine and warm it up to operation temperature
4. Turn igniton switch OFF and wait at least 10 seconds
5. Confirm Gas Pedal if fully realeased, then turn igniton switch ON and wait 3 seconds
6. Fully step on and release gas pedal 5 time within 5 seconds
8. Wait 7 seconds and fully step on gas and stay on until MIL stops blinking and is steady.
9. Fully release the Gas pedal within 3 seconds after the MIL has turned ON steady.
10. Start engine imediatly and let idle. Wait 20 seconds.