transmission not shifting correctly on 2003 Hyundai Accent

When the car is upshifting is goes smoothly from first to second but then hesitates and shifts very hard into third. If you stop relativly fast it downshifts hard-like someone has hit you.

Asked by for the 2003 Hyundai Accent
Have the transmission checked out, might be low on fluid, or have a failing sensor or solenoid. Are any warning lights on or flashing?