I did every check. Clean the whole intake manifold. Bite the bullet and buy the expensive IACV but still surging idle persist. No check engine light though. Car runs very well in the freeway too....replace TPS too ....anything guys I appreciate I want to tackle this not to skip or ignore the problem.

 

Did you spray carb cleaner on the hoses and around the gasket areas for the intake? An air leak is most likely your problem and could've saved you lots of money if that is the cause.

 

You did EVERY check?

Air in cooling system?
Clean throttle body bore & throttle plate?
Throttle closes COMPLETELY?

Did you set the BASE idle? (or did you simply try to adjust the operating idle)