Car jerks

You might be low on transmission fluid.

I'm not I checked that

There was a TSB concerning this for a software update. Some people have had luck with the update and others not so. Also depending on how much mileage is on the vehicle may be a sign of internal wear of the transmission such as pump, clutch plates, etc. I would suggest as mentioned checking the fluid level but this slip bump you describe is widespread with the 6F50 transmission. It usually only happens here and there usually when cold but it can occur at any temperature.

don't use a conditioner , swap out the old fluid for new the best you can