It's up to you, meng. I would call the DMV and ask them about the idle and see what they say. I don't think the car is acting funky, it's just a bit pulsy...I would want to check out the throttle wheel stop screw though.
I'd do a couple of things. I wouldn't spend any more money on this mechanic.
I don't know how much the idle is varying, but for the price of the mechanic, you may as well get it tested, just to see what is what. Maybe it will pass and you won't have any further problems. If it doesn't, at least you will have some idea what the smog guys have an issue with.
On the idle, you had one post which said that it stabilized for a short period of time, at 500, right? On my wagon, it would idle sort of steady, until the engine began to warm up a little bit. Then it would go into it's hunt cycle. Mine ended up being a bad IACV valve. The clue is it should not allow any air to pass through it, when it is off, disconnected from the ecu.
I would either pull it off and recheck it, or for the price, go to a pick your own part and pull one off, check it out, pay the few bucks, put it on, in replacement and see where your at.
I went back to doing almost all of the work on my cars because:
A. I can't really afford to pay someone else to work on them.
B. It seemed like almost every time I had someone else work on them, they would end up having issues which were either the problem I had paid to fix or something else which was induced by the mechanic. In either case, I almost always only got it finally fixed, by fixing it myself and if it takes 3-4 times for me to figure out what the problem is, then I just figure that is the cost of learning, to me. However, when I'm done, I at least have a clue as to what I did or did not do and what or what might not be the consequences.
Best of luck to you.
p.s. I do have a mechanic I use, when I get down and desperate, but he is a very experienced, very methodical mechanic and very much an exception.
Mine likes to hunt after its warm too. I just had the IACV off and cleaned it. As it happens, I blew into it to see if there was any more cleaner trapped and I did notice some blow-by (and a horrible carb cleaner taste too!). So if I understand you correctly there should be NO air blowing through, is this correct? I'm not sure which hole I was blowing in, does it matter? I've been trying to track down this air leak and this is starting to make sense. Then again it could very well be something I'm overlooking. I'm going to go through TomO's list and see if there are any more culprits lurking. If you get a chance, let me know about the air leak in the IACV. Thanks!
Well gentlemen, good news! He continued working on the car. He took the throttle body apart and cleaned it and viola, the idle is no longer sticking! It still is idling high but not roaming anymore. He said it might improve once all the stuff he sprayed in the throttle body has burnt off. And he said he'll do an adjustment in a few days.
I passed inspection with flying colors. I believe the co2 was 5.28 out of 20. Guy said o2 sensor is good! more lata, I gots to go.