Throttle sticks at 2000rpm when let off accelerator

[Smi]

So i have a corolla 1.4vvti e12 2004.

when i rev above 2000rpm, let off the accelerator, and as the revs come down the rpm sticks at 2000rpm momentarily.

is this an idle control valve issue? Throttle motor? Ive tightened the throttle cable as it was very slack and is no better. 

anyone help me? Thanks in advance 👍

[Red_Corolla]

Don't tighten the cable too much, there should always be a bit of slack in it at rest. Twist the throttle open from under the bonnet a few times (engine off), make sure it snaps shut quickly and hits it's stop every time you let go. Also make sure the cable isn't sticking, they sometimes break a strand and start to stick inside the sleeve when they get old.

Throttle checks aside, it could be the IAC valve sticking open, but I think a vacuum leak is probably more likely.