really bad happened once when i got new set of tires installed from al amir workshop in al quoz i had to go them for a week everyday just to align them as they were very busy wanted me to leave the car for a week.
If its actually a jerk at specific speed, check if air filter need cleaning or Air flow meter need cleaning. If its more on wooble then it could be from unbalanced tire, just get the tire balance and you will be fine. I think its wobbling issue as its jerking the steering too, so balancing in 100 dhs can cure your problem.
the term used here is called sleepy power assist. which is caused by combination of contaminated power steering fluid and a power steering pump that is giving up.
to Fix this you should flush the power assist system and see if there is any improvement and If not it is best to replace the pump itself.