vibration caused by acceleration

ya when i reach speeds of around 70KM/H and then speeds over 100KM/H, while lightly pressing down on the gas, i feel a sort of vibration , not on my foot persay, but like from the car. Its like if u go over those little bumps on the highway that r supposed to slow u down.
does anyone know wat im talkin about? 89' PA by the way.

where do you feel the vibration? ie.. steering wheel, seat...

like i dunnoo, not in the steerin wheel , like i guess from the floor or somtin, and the seat. its like an odd feeling , i cant xplain it

like if you can't xplain it I can't help. like you might take a look at this www.gsp9700.com