Recently purchased a used 2009 Brabus edition with 30,000 miles. Occasionlly when comlpetely stoped and then apply gas to move forward the car will jump several times like a Kangaroo and not take off smoothly. Notice really bad in stop and go traffic this morning. Could not get a smooth launch when having to edge a couple of feet to car in front of me. Feels like a standard car with clutch and not giving enough gas or something jumping forward. Its worse when just applying a little pressure to the pedal to go forwad if that makes sense. The car will jump back and forth and then go. Any info or advice would be great. Putting 93 ocatane in. I do have a go pedal installed but occured even before that install.