Q: Rough idle, fluctuating rpms, stalling

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Several weeks ago we took our van to the mechanic because of a rough idle, and diesel like noise when idling. He informed us that the noise was normal and because it wasn't throwing codes and idled fine while he had it, he couldn't diagnose the idle issue. Fast forward to this week, and the van stalled out as I was waiting to pick up my daughter from school, idling in park. I tried to start it several times and while it did start, the rpms would immeadiately drop and it would turn off again. Eventually I got started again. And it drove fine. Took it back to the mechanic that day. Next day he calls and said he can't find any obvious issues, and that he could start poking around but it would possibly cost a fortune in labor just to pinpoint problem. We pick it up and it was fine yesterday. Today as I was waiting in line for my daughter again, I noticed the rpms fluctuating and the shaking was happening again. I turned off the A/C recirculator, and rpms leveled out and all seemed fine.

My car has 79000 miles.
My car has an automatic transmission.

Hello, thank you for writing in. The vehicle is struggling to keep up with all of the different accessories when the engine is idling. This is typically due to an issue with the air intake, fuel intake, or the sensors that monitor and control them. Start by having the vehicle scanned for codes at your local automotive parts store, or by a different technician. If no codes are present, attempt to clean the throttle body, idle air control valve, and the throttle position sensor. If there are codes present, then you can use them to point you to the issue at hand, and take corrective action from there. For more help with diagnostics or resolving the issue, contact our service department to schedule an appointment.

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