Idle speed problem

[oldskull]

Hello all,
I got some problem with my idle speed. First of all, I am too noob with car. So my problem is, when my engine warm the idle speed going up and down between 1500rpm and 1700rpm. This happend only when the car idle/stop and while driving is ok but when I press clutch pedal its happen again.

Things already done:

Flushing my radiator few times, resevoir coolant are about full line now.
Checked and renew few rubbers that connected to TVIS. Just found 1 rubber are leak.

I dont know which 4age engine I got in my car but you can look here:
http://oldskull.sytes.net/ul/DSC03965.JPG
http://oldskull.sytes.net/ul/DSC03915.JPG

I hope I can fix it myself with your help. I am going back to the first owner, but its take awhile to go there seems he also busy with work.

Any help and suggestion are welcome, thanks