5 speed. On start up I'm hearing a low level humming noise coming from the front. Then when I come to a stop, the idle is rough. It will go from about ~800rpm and drop below ~500rpm and almost to the point where it feels like it's going to stall. Then it revs on its own up to ~1200rpm before settling back to ~800rpm. Then a few seconds later it will drop again to below 500.

A quick search says maybe idle air control valve? I live in Nevada where it can get dusty.

Any ideas on the issue would be appreciated. Thanks.

I'm taking it in on Monday. Should I suggest that the idle engine control valve could be the problem or just tell them symptoms and let them figure it out?

 

Have you disconnected the battery recently?

 

No. Just now wrench light came on as I pulled into my garage and it stalled. Manual says "throttle control"....or something.

 

an alternator going bad can cause these issues as well. possibly battery. have them checked. good luck

 

pull codes, most likely bad throttle body

 

Thanks for the responses. Picked car up today. They found bits of plastic in the maf sensor passage. Cleaned maf sensor. Everything seems good now. Sadly, not covered under my extended warranty as the part wasn't broken. $200 later.

 

glad it was not something serious! $200 is not bad if the problem is fixed.

 

Thanks. Yeah, I guess it could always be something more serious and expensive. Kind of bummed the warranty didn't cover it. I asked the guy what if this happened to a brand new car? You're not fixing it under the warranty? I think I would go nuts if my brand new car had this problem and the warranty didn't cover it. The warranty should cover the same at mile 1 or mile 71,999.

 

My Mustang

 

Warranties are for manufacturing defects. Debris in the sensor is not a defect.
Warranties, on cars anyway, are for quite a long period of time in comparison to what they used to be. And they also cover ALOT more than they used to. Nobody can cover a product forever that generates wear and tear from daily use. They would either go bankrupt, or have to charge a whole lot more for their products.