Riaan, A brackbooster is a good option But your problem is the brake lines. You replaced the strats with the flexible pipes that came with it? The pipes are periched on the inside and thus work as a one-way velve, it is worse when the brakes are hot from stopping hard. When you brake flued goes into the caliper but the pipes prevent it from going bake thus stopping the ute.

Replace the flexible bracelines in the front, and your prob will be solved. The new discs and pads help this prob to be worse also.