2001 Toyota Sienna engine idle sometimes low dies out.

Hi I got a 2001 Toyota sienna with a big problem. first of all it starts up good sometimes like in the morning. and like today right after I drive if for a couple of miles and shut the engine off. later I start the engine and it couldn't start. I got to give it gas and to catch idle.



Sometimes I would just start the engine and it would just start. I don’t have any rpm gauge but I use the generic scan tool I have to check the rpm with the live data it shows. The idle stays very low at 440rpm to 500rpm. I also have a voltage gauge hooked up with it. At the same time the voltage stays at 12.2 to 12.4 at the lowest as with the rpm. Then I put it to drive the engine dies. I start it up and same thing happens low idle I have to rev it to get it going. I found like a cure I rev the engine for a while and then I see the idle carries itself and the voltage goes higher like 13.5 to 14.1 volts good. My father told me it might be an alternator, I checked the alternator he replaced it but still same problem good. The batt was slightly low charge but we charged it but it works better charged than before.
Sometimes it just cranks but no start and I need to give it slightly gas to start the van.

I cleaned the throttle bodies and sprayed the iacvalve for a while. Like a couple of times.
Worked but it still intermittently happens.
Is it something big like fuel pump or something expensive?
My father spent money already on an alternator but same issue.
Okay I checked the Haynes book they says put to neutral/block wheels/and to jump the data link connector under the hood when the engine is running the engine should rev higher than normal for about 5 seconds and go back normal. It says it’s insuring that the iac valve is working.

So I tried to get the van to do so. Okay when the engine starts up with a good idle the test works it idles higher than normal for 5 seconds and goes back to regular idling.

Then I tried jumping the DLC 1 under the engine when the engine was like 440rpm lower idle when it happens. The engine don’t rev like what it should do. The connector is jumped.
Does that mean the IAC Valve is bad? The book says it is bad but why does it happen intermittently?


Need help comments on what this problem is.

Thanks jon.