Seriously try new pads. Pads that have been contaminated are never 100% the same! The same goes for the angle/wear of them, if there's an angle theres less pad = less surface area which inturn may result in less bite and hold. Also make sure your disc isn't contaminated and clean it as well as you can! Make sure you don't touch it with you hands (within reason). But number one priority I would say is new pads. If it's still crap with new pads and a new rotor your doing it wrong! What hope is it out of interest?