power steering sticks from side to side

the faster I go the harder it sticks if im going straight and well say 70 kmh im holding the wheels maybe with a little pressur to one side to keep straight then whem I try and turn it is stuck and sometimes real hard to turn the wheel ive had play in the hanle bars sence new but now this I know where the play is its the pinch sleave underthe eps box but it still shouldn't do the sticky shit when I first git it I checked all the bolts wireing I dielectric greased all conecctions the battery terminals and it has anew battery ive had it flashed with the newest program its a 2013 850 xp le