2002 Dodge Durango front brakes smoke and cant go over 40 w

owne a 2002 dodge durango 4.6L. it has about 89,000 miles on it. just bought it used. recently when i drive it the front brakes begin to smoke, i can not drive faster than 40-45 miles per hour, it gets worse when the car heats up. smells like buring rubber. supposly the barkes where replaced before i bought the car in feb of 2008. what could it be, it get everything from the calipers to the brake pads? what could it be help...want to drive my car....