This could be a problem with your vehicles Throttle Position Sensor 2 (TPS2). This is the second TPS that your vehicle's Power-train Control Module uses to determine the throttle angle. Also there is a possibility it could be a problem with the throttle plate's return spring.
I have included in the diagrams down below the factory troubleshooting guide for the throttle control system in the diagrams down below. Please go through this guide and get back to us with what you find out.
Images (Click to enlarge)
Thursday, April 4th, 2019 AT 7:02 AM