Car bucking

Hi

Hyundai Exel 4cyl 1998 1.6 150,000k

Car Idles ok.
When I accelerate from go, car is bucking. When I put my foot down, there is no power in the car and bucks a little. When at a good speed 90+ km p/hr car runs ok.
Seems to be when I accelerate is when the car is bucking.
Friends say it is fuel filter, spark plugs, leads?

Can anyone pse narrow it down for me? If it is a fuel filter, where wld I find it in this model car?

Thanks very much.