[grandfunk]

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 itself 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?

[pcfrisch]

Could be a loose CAI or MAF sensor. Have you checked to see if everything was tight?
Oh, and welcome to AFM!

[USMC92]

Welcomle to the site! Sorry to hear of your trouble. I have had mine for two weeks this Friday. I have a little over 300 miles on it. I would not worry about it to much unless the dealership gives you the run around. Hopefully they fix it for you rather quickly. Can not blame you for being upset. Let us know what they say. The only thing I have noticed with mine is that in 3rd gear I get a little vibration when foot is not on the accelerator. I am going to ask dealer about it.