Car stuttering when slowing down/speeding up

What is your question?

When i start up my car and speed up at around 5-15 mph the car will stutter very hard as if i'm running over something and when i slow down using the brakes it does the same thing. This only happens the first few minutes that i drive the car. I have a BMW 2014 328i rwd

How long has your 2014 BMW 328i had this problem?

just got my car, preowned