I am finding when my mustang has reached normal operating temperature the engine is idling slightly rough from 600-700rpm. I've seen 5 other 5.0's on youtube with the same issue but there is no mention of any solution.

I have tried disconnecting the battery, performing the idle relearn procedure, checked the obd2 port (no issues), checked for vacuum leaks, cleaning the throttle body and mass air flow sensor and no luck.

When the engine is cold, driving in first between 1000-2000rpm, the car jerks as the revs fluctuate.

Can anyone help me on this?

 

My 11gt/cs does the samething, in addition its rough at 2000rpm. I've had it looked at by two different dealers with no resolution. Both dealers agree its missing (rough) but neither could solve it. Last one had it a week, in the end they suggested I chip it, might fix it they told me. I just purchased a ProCal program last week and plan to install it this weekend. Keeping my fingers crossed

 

If this is of any help, my car has a tune and I know with the handheld SCT tuner it's possible to modify/check a variety of things on the car. Also in terms of idle settings.

 

Please let me know if the procal tune fixes it.

 

I had a similar issue, but it turned out the plug I used when I did my own sound tube delete had popped out of the intake tube. I was getting ready to clean my MAF sensor when I spotted it after a day of the car randomly dying/going into limp mode.

 

Follow-up
Installed the ProCal tune this afternoon, made no difference in the idle or surging at 2k rpm.
Initially thought it helped with the surging in first gear while idling around the local mall parking lot but by the time we headed home it was surging as always.
Under hard throttle it was pinging at 5k so I went back in and change the octane to "Y". Pinged worse so I went back to " N". Tank has 92 in it but that's 10% methanol here in the Great Northwest.
Local Cenex has non methanol, I'll try a couple tanks of it before I totally condem the tune.
At least it did get rid of the skipshift, of course I had to get under the car and plug it back in before I could install the tune.
On a positive I installed the GT500 axle back's that came in the kit. They are just right, zero drone.

 

Have you guys addressed this with your service managers? They’re in the best position to ensure a proper diagnosis, and will be able to provide available options and/or coverage for any work needed. Also, remember repairs done at a Ford Dealer come with a 24 months/unlimited miles warranty.

Deysha

 

I've not had the chance to take it in over Christmas. Once I get back I will take it to the dealer.

 

Ok, trackpack13gt. Keep me posted.

Deysha