Please help - Mustang running rough

[Leigh_bullitt]

Hi Guys
I have an intermittent problem where the car feels a little rough and lower on power. Almost like it loses the torque in higher gears.
Problem is it’s intermittent and happens 40% of the time and then back to normal again.

one thing I have noticed is when rough if I reset the dtc codes it runs smooth again until 4 or 5 drive cycles.

I know the readiness resets so could this be the problem ?.
possible upstream O2 sensor giving false readings once readiness check completes ?.

thanks

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