Very likely to be the idle control motor. We live in a maritime environment, and invariably after a sitting for a week or more our Terios has idle problems.
1. Remove the air filter assembly
1a. release 5 clips, free the top and element (note white corrosion)
1b. remove 3 10mm bolts
1c. detach 4 hoses and sensors
1d disconnect 2 electrical connectors
2. Remove idle control motor (engine cool)
2a Remove 2 water hoses
2b Remove 1 electrical connector
2c Remove 4 Phillip's head screws
3 Disassemble idle control motor
3a carefully scratch alignment marks for accurate reassembly in the black plastic motor stator
3b Carefully use a hacksaw to cut flat screw driver slots into stator retaining scres
3c Carefully remove the screws
3d Carefully wiggle black stator section off main assembly. exposing the rotor of the control valve (note there is some magnetic attraction)
4 Fixya the valve. (if it doesn;t spin freely this is definitely contributing to high speed or hunting idle
4a valve rotor should spin freely. If it is sticky or stuck gently try to free it. Use penetrating oil, brake cleaning fluid or turps.
4b Manipulate the rotor until it spins freely. It will spin like a top when fully lubricated.
Reassemble in reverse order. Be sure to fill with coolant and bleed the throttle body.
Thanks for looking!