The car has been brought to a mechanic to check and repair for the jerking
problem while driving onto a hill.
the mechanic ask me to change an Oxegen Sensor, and do a tune up.
before I send my car there the idle sometimes is not stable, especially in the
morning but after ideling for 5 minutes it is fixed around 750rpm.
however after this mechanic changed O2 sensor and cleaned the Throtal Body,
it seems the car can never idle at 750, it always shakes, the idel is between
800 and 700rpm. the emission is not smooth. I can feel the frequency of the
jump and down of the idel and emission when I sit inside the car.
it is really upset. cause after spending 270 bucks nothing gets better,
the car still jerks and the idle is even worse!

This mechanic give me other advices: either is the IAC valve bad or my ECU is
bad. but I just can not believe him any more.

my question is how to test the IAC is bad? when I remove the hose from IAC to the air filter box, I heard uncontinued(not smooth) air flow sound.
this sound matchs with the emission problem.

I just wonder is there any other work that can be done by myself before changing
an IAC? or if I have to change it can I do it myself? It looks not hard to change right?


Thanks you guys.