Hyundai Repair: hesitation/surging, secondary ignition, hesitation

Question
I have a 96' sonata v6. During acceleration or slowing down the engine runs smoothly. When a constant speed is maintained on a flat or downhill
road the car hesitates like the ignition is missing. The transmission has been checked.

Answer
If you think you have a misfire, you should start with checking the secondary ignition components.  In this case, that would be coil, cap, rotor, plugs, and wires.  By far, the largest majority of misfire issues are ignition related.

Also, do you have a check engine lamp on?  If so, do you know the stored code(s)?