The plastic top tank and the aluminium core are easily separated, you can read about it here:

https://www.s2ki.com/forums/index.php?showt...t=0&#entry80007

But back to the real issue - I have bled the cooling system twice and there is definitely no air lock.

Any other ideas? Maybe something wrong with the IAC? Is it possible coolant could have splashed into the IAC motor and caused a problem?

 

Clean or have your icv replaced. true it has coolant running thru it but they can get dirty inside and cause idle problems. heard many stories about this problem. good luck.