Drivetrain 2007 mustang gt manual shifting issue!!!!

Hi all!
I need help or advise!
On my 07 gt convertible with manual trans, when I step on a gas (full throttle)
Shifting from 1 to 2 is ok
From 2 to 3 is ok
But from 3 to 4 is some kind of mystique because when I am trying to shift from 3 to 4, gearbox moves me as I think to 2-nd gear and car starts to brake (like engine braking) with strange sounds.
Everything happens only when you step on (full throttle)
Have anyone something like that ?
And how I can fix it ?

Hey!
No one has such situation ?

Bullitt95 said:

You could be experiencing excessive movement of the body-mounted gear shifter due to worn engine mounts or a worn tranny mount.

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Maybe, but there is only 33k miles on this car
Seems there is only my problem)) no one here never has such issue
Also everything was inspected on the car and there was no any problems with mounts