I have a 2001 Hyundai Sonata with 88K, new tires, new tranny, everything good so far until a month ago when i started my car and let it heat up for like 2 minutes then began driving i got to a yellow light and i picked up speed a bit to make the light then the car lagged trying to change gears and made a hard jerky movement and it felt as if i was losing the gas pedal. Also that same jerky movent happened on the HWY i picked up speed from 65 to 80 while doing that i got the same jerky movement. It feels bad, it feels as if i were to be pressing the brakes hard and letting it go really fast. Any ideas what this might be? thanx.