[PonceDeLeon]

Update -
My daughter and I drove the mustang about 50 miles today with the OD disabled, did not have any problems with the transmission. A couple times the idle did hunt around when we were stopped at lights, seemed to be worse with the AC turned on.
BTW my supra was a 3.0 inline 6 turbo (rest in peace) .

[P4452]

Originally Posted by PonceDeLeon

Update -
My daughter and I drove the mustang about 50 miles today with the OD disabled, did not have any problems with the transmission. A couple times the idle did hunt around when we were stopped at lights, seemed to be worse with the AC turned on.
BTW my supra was a 3.0 inline 6 turbo (rest in peace) .

That it should. They're damn good cars, just not the same quality as many Mustangs.

You need to take the belt off and spin all of those accessories individually to see where the problem is, and if it is even an accessory. If anything rattles, squeaks, grinds loudly(a little grinding sound is to be expected), etc. you need to replace it or have it replaced. This includes the tensioner. It should release smoothly and silently.

[P4452]

I forgot to add:

My tensioner was going out and you couldn't hear it unless the A/C was on and the car was revved slightly in manual second. The higher torque was causing it to jump. So, just because you can't hear it in the cockpit doesn't mean it couldn't be happening under the hood.