For backstory I've had my 10 GT for less than a week and it has 300 miles. A few days ago I started to get an unstable idle and every so often the car would surge slightly while in gear at part throttle. It was worse when cold but didn't go away when hot. I gave the benefit of the doubt and tried to run the tank low so I could refill with something I put in and knew was good.
So I filled it up with premium hoping to alleviate the problem and now it has become worse. Worse to the point to where the traction control kicks in due to the strong bucking of the car back and forth. No check engine light or any abnormal indication besides the way it is actually running. The only thing I can do is push in the clutch and let it fight itslelf for a bit and then try to keep going.
I've obviously called the dealership and am taking it in tomorrow to have it looked at. Hoping its something simple.
What I was wondering was if anyone had any similar issues. I've owned 5 mustangs including this one from varying years and have never had an issue like this. My 90 coupe with 100,000 miles ran better so I am pretty upset at the moment. Any thoughts?

 

Just take it to the dealer. It is probably something simple. I had a Ranger that brand new had a problem. Took it in, the dealer changed some sensor (dont recall which one) and the truck ran perfect for 85,000 miles before I sold it. Electronic sensors will have issues and that is life. I know it sucks on a brand new car, but it will get fixed and run fine in all likelyhood.

 

There are a couple guys with similar issues it sounds like. Maybe they will chime in here. Good luck and please let us know what the dealer says for record.

 

I'm one with a similar (although less severe sounding) issue. Took it to the dealer today, the shop manager rode with me and it almost stalled several times. He had no comment at this point, I'm just glad it misbehaved for him. Hopefully know something tomorrow.

4500 miles, just started about two weeks ago and has gotten progressively worse.

 

Good that you got the dealer to verify the issue. Keep us posted on the culprit

 

Got a call from the dealership and they are saying nothing is wrong. No codes or unusual stuff like that, they took it on a road test (without me) and couldn't reproduce the problem. I'm guessing it is because they weren't in stop and go traffic because thats when the problem really manifests itself. Besides that, the person I spoke with said its absolutely normal for a car to run poorly and have problems with idle off and on for the first thousand miles or so. This problem is not off and on, it happens every time I drive the car. It happened on my way home from the dealership just like I knew it would. Until it gets bad enough to actually throw a code these clowns aren't going to do anything. I'll find another dealership and I'll update the thread as things progress for informational purposes.

 

Grandfunk - If you didn't see in another thread, my problem was caused by some sort of leak in the air intake, letting in air unbeknownst to the ECM. I did insist the shop manager ride with me so I could demo the problem.

That line about the rough idle on a new car is perhaps a new low in dealer BS. Good luck, I really hope you get your car fixed soon.

 

sounds like an idot,any new car i have owned has not acted poorly or i would have taken the damn thing back.

i would check your air box and intake hose clamps,make sure they are tight,esp. the throttle body hose clamp.

 

Where are you located in NY?

I would try tightening up any place there could be an air leak. Also is the gas cap on tight enough? Try disconnecting the battery after these steps for 30 mins and let the ECM reset, then see what happens.

 

There's a gas cap on the 2010?