So my daughter's '00 stalls while sitting at lights (three times over the past week).

It was throwing a code a few weeks ago, so I replaced the PVC, it's boot and hose) and cleaned the MAF and the code went away and she was running good.

Now she stalls at traffic lights, AC not on, no idiot light on, no other symptoms.

Ideas?

Thanks in advance for any ideas!

Fuel filter? Has it ever been changed?

Air intake hose may be needing replaced.
Mine will stall if it's come loose.

How many miles since plugs etc. were changed? Has it been raining in her area lately? I've had several older vehicles that would stall when it was wet if the plugs etc were old.

It's a classic clogged or dirty Idle Air Control valve. That's the valve on the underside of the throttle body that has a vacuum line and coolant lines going through it. Debris falls through the air holes in the throttle body and then clogs up the valve, not allowing enough airflow to pass through to maintain idle speed. Only will stumble or stall when the engine is fully warmed up, otherwise when cold it'll open more to keep from stalling.

There's some threads on here that will help if you search "IAC cleaning" but the gist of it is to remove the throttle body, remove the IAC (coolant will leak out but not very much as long as you keep the hoses upright), clean out the valve, replace the gasket and reassemble. I don't recommend replacing the IAC unless you absolutely have to because the part costs $250.

Should be $100 or less. Just replaced mine last year, believe I got it from partsouq. I imagine it would be more if youre going directly through a dealer, they always love to tack on another 50% but thaf still sounda kinda high. 96-00 don't have an integrated IAC/TB like 01-02.

As Gamefreak said, IAC just needs a little cleaning, its easy peasey and takes about 5 mins Do the butterfly while you're at it.

The reason why members say take the iac out and clean it, because there actually a electric motor that open and closes the valves. You may risk damaging that motor if cleaner makes it's way to the motor.

Plus having the iac out is a better way to getting at the angles to properly cleaning out all the carbon and oil.

After cleaning give time for the ecu to learn proper how to idle again.

Maybe the price changes. The one I bought from partsouq last year was $212 plus shipping. I had reason to believe mine had bit the dust (it hadn't, was the TPS).

What year is this 4runner? OK. I see. it's a 2000.

I have a 2005 4runner and it has never stalled.

I would guess fuel-related. Possible fuel pump. Fuel filter?

I'd ask around Toyota dealer or mechanic.
Advice above looks good?

Get a cheap OBD reader and watch the PID's for fuel trim.

if the fuel trims are way high, it could indicate vaccum/air leak on the intake.
If its running super lean, you could have leaking injectors.

No code stalls/failure to start are usually something wrong with the A/F ratio. Could be IAC too as others have suggested.

So, clean out the carb/IAC, maybe look at some spark plugs.

Your 4th Gen advise is not wanted here. Go back under your bridge you troll.

I swear some people post just for the sake of posting

IAC valve. Check that, thanks to more experienced folks.