Toyota Repair: RAV4 1998, air intake hose, phillips screws

Question
Hello, I have a RAV4 1998, 4wd 4 doors (manual gear).
Here is the problem I have.
When I stop at a red light, the engine idle decreases to its normal value (around 750rpm) then ramps up to 2000rpm and stays such high.
Sometime when I drive at constant speed or when I begin to accelerate in 2nd or 3rd gear the engine has some hesitation.
Sometime when I shift from one gear to another, the engine rotation speed stays high.
This seems to be something like to much air intake or something like that.
I have read in your answers that this problem can be caused by an IAC problem, I wanted to know if an IAC problem can cause the engine rotation speed to be too high instead of too low ?
The toyota dealer told me that the iac needs to be replaced but at 700$ the repair I would like to do it by myself. I took a look at it and it does not seems to be difficult to change.
Can you give me some advice on how to change it? I located it just under the throttle valve (under the little square hole in the air intake) but I would like to know if there is a special process to follow.
Thank you very much for all your advices, you're the Toyota king :)
Cheers.  

Answer
If the ISC valve is the problem it can be cleaned, remove the top of the air filter housing and the air intake hose connected to the throttle body, remove the cables attached to the T/B remove the four 12mm size nuts holding the T/B on and then disconnect the coolant hoses from it and the vacuum hose, once it is off take off the four phillips screws on the ISC valve and remove it then clean the inside with some throttle body spray cleaner and reassemble everything.