I have to say that I would look into 2 aspects , the first one is the flywheel resurface , was it done correctly ? The other is the clutch , I have had new clutches from ford that slip until they have had the first heat cycle through them , they have not had the final cure until this cycle gets put into them and so if driven gently for the first 100 miles then they do recover as the spinner hardens up and then can give the coefficient of friction that is required . Just my thoughts .