1998 ABS problems.....

okay i just bought the truck, i knew there was a problem with the brakes on it, and told them, they discounted the price where i was comfortable to buy it. I replaced the rear abs sensor that goes into the rear axle, but the brake pedal still pulsates from 15mph -0mph rotors are not warped, there fine along with the rest of the brake system except for the abs. when i take the fuse for the abs out of the circuit the brakes work just fine, thats my temporary fix so im able to drive it,but my question is this what else can i replace to get the abs not to kick in when its not needed? abs light comes on occasionally, but stays when the fuse it taken out obviosly its not the right thing to do but its a temp fix for a big problem. Any help....

its a 1998 ranger flarside
3.0 liter
5 speed
4wd
single cab