2001 model engine stalls at idle

Friend of mine's 2001 Sienna with over 100K miles started giving him a problem last week. It started to stall when he stopped at the traffic lights. To avoid the stall, he has to press the gas pedal to rev up the engine while the other foot is on the brake. Took it to the shop but they did not know what was causing it. They wanted to disassemble the whole engine intake and other engine related items to troublshoot. Since they had no idea what to do to fix the problem, he decided not to have them do it there. Anyone out here have any clue on this problem/fix.

Wajangchang

Check the EGR valve for carbon deposits to be cleaned out as one possible solution. Bad vacuum leak is another possibility.

Thanks Typesix, I will forward your recommendation.

Wajangchang

The problem was fixed by replacing the idle valve (I have no idea where this is and what it looks like). The local Toyota dealer's service shop charged $600 for parts and labor. Additional $550 for timing belt replacement.

Wajangchang

600 dollars holy crap!!! my Dad van has stalled three times now at a light. Is this a problem he should expect to worsen?

First, the idle stabilizer is a very simple device that doesn't break easily, but it does get dirty and stick. I suggest you get a service manual to locate the valve, but it's on the right side of the engine beside the throttle body if I remember right. Remove and clean it with brake or carb cleaner. I think it's safe to use a carb parts solvent bath on it as well (check for plastic first). Once clean, make sure the piston inside moves up and down freely. Clean your throttle body thoroughly while your at it. Total repair should cost less than $20 in materials. The valves should last 20 years or better. Check the service manual for additional checks.

That's very typical for dealer. If you don't do your homework find out what's wrong with the car, then the dealer will charge you super high tuition.

I cleaned my throttle body, idle stabilizer valve and a few other items a couple weekends ago. Some advise on lceaning the idle stabilizer valve.
1. It is connected to the throttle body. Remove the throttle body to access it.
2. Carborator cleaner works great. The part you clean is like a revolving door and it does stick easily.
3. Remove the rubber gasket between the body and stabilizer before you clean it. Carborator cleaner will make the gasket swell and it's a bear to get it back in if swollen.

Thanks, Doug Tatham!! Took off the electrical part off the IAC valve, sprayed the heck out of it with carb cleaner until it moved freely, and put it back together. Idles perfectly. Did not even have to remove the throttle body.