I have always told people that it is not the idle control valve at fault for
high idle speed... yet people still do that the first thing.
Majority of the reason for high idle speed is two thing... depending on the
models and years.
First thing to check would be your overload relay fuse... the only relay
unit you have in the fusebox or behind the battery... that has a red fuse on
the top... another telltale reason for suspect is your antilock brake light
The second reason and most common cause of failure is the idle control unit.
Get a reman unit.