My car started doing this thing were when i'm driving (the speed always varies, usually between 30-100km/hr) where i can't speed up and my car slows down. I will lose control over the speed from 1-5 seconds and then it will jerk forward like it's gaining speed but then will stop working again and jerk forward. This will happen for 30 seconds to a couple of minutes. I have taken it to 2 different dealers and they say it's fine as it doesn't happen to them when they take it for a drive. If anyone knows a solution please let me know!