I30 is sometimes stalling

[TKouT]

When I am slowing down or at a stop, it try to stall. I have no check engine light and my tachometer fluctuates when I am idle. Sometimes before it stalls, It surges then drop to around 300 rpms. I notice today, that even through it didn't stall, my rpms drop drastically and fluctuated back and forth, and then went to 1000 rpms , which jerked my car ( I had my foot on the break).Also my tachometer floats between like 450 and 700 when I am idle, even through it doesn't stalls. What could be causing this and is it ok to 300 miles out of town?

I took it to a mechanic a little over a week ago, when my check engine light was on ( which through codes P0325 for Knock Sensor, P0401 for the EGR tube being clogged with carbon, and P1401, which said Throttle body Position Sensor) and I know he cleaned my throttle body, intake manifold collector, my egr guide tube and replaced my egr temperature sensor and throttle body position sensor. I took it back to him because it is still stalling. I cleaned my mass air flow sensor myself with rubbing alcohol and a q-tip, but it wasn't dirty. I have a factory service manual, but I have been told it is either my mass air flow sensor or my IACV, but my mechanic doesn't want to replace both of them because he says they will be throwing codes. Is that true? Is it safe buying theses parts on online or going to a junk yard and getting them? I have been reading that the MAF may not throw a code. I will drive it some more tomorrow and see if I can give a more specific description of the problem.

[maxhopper]

Just remove the IACV and clean the carbon out of it. You should be good to go.
Also make sure to replace/reinstall the IACV gasket correctly following removal.

[loystock]

Strange that your mechanic does not warranty the repair job. Most shops will give at least 3 months warranty. BTW, cleaning the TB, if not properly done can damage the actuator/sensor as too much cleaner can seep into these assemblies. NEVER spray cleaner directly into the valve assembly (use a rag for cleaning).

When you service the IACV, make sure you check resistance of the stepper motor as a short circuit can easily 'fry' the ECU (IACV driver (power transistor) inside the ECU). Also, a dirty IACV and failing MAF sensor may not necessarily throw a trouble code.

[TKouT]

Thank You for replying. It is now doing something else ( now I realize) . I recently had to move out of my apartment, so I had to use my car. Now when I first turn it on, when in park idle, it is revving 1500 rpm, more then usually. When I put it in drive it drops to 700 rpm and sways a little ( give or take 100 rpm). But when I was moving, it stalled while I was at a light. I cut it back, a couple seconds later, it shut off again ( both times it sways to like 1000 rpm then down to 500 rpm) Then I turned it on again, took it out neutral and put my foot in the gas and went. While I be driving with my foot off the gas, it would be at normal rpm and then drop and come back up, when I put my foot back on the gas. It never cut off while I am accelerating. I am going to take it back to the mechanic on Monday and tell him what is happening, he said he already cleaned the IACV. Could the mass air flow sensor be causing this, or is it definitely a faulty IACV? ( I would replace both, but they are both expensive)

[maxhopper]

It sounds to me like the IACV.

[NutriaforBreakfast]

If you have a multimeter you could try checking the voltage and resistance of each
of the components per the FSM;

For the MAF
http://www.nicoclub.com/FSM/i30/1996_I30/ec.pdf

For the IACV
http://www.nicoclub.com/FSM/i30/1996_I30/ec.pdf