Toyota Repair: 2000 Tacoma Brakes, metallic brake pads, seal leaks

Question
This truck had 15K miles when I bought it. It is a V6 SR5 package. Today there is 81K miles on it. I am on my third set of front rotors. The current set is 8 months old with new semi-metallic brake pads installed at the same time. Problem, they are now warped as I get pedal pulsation. I took them to the local machine shop last weekend. The tech told me one can not be turned as it is warped by 40 thousands. Question, what the heck is going on with these brakes?
I have replaced all the mounting hardware, hold downs, pins, etc. I have cleaned and greased the sliders. Do you think I should use ceramic pads? I do not get any heat build-up on the rims or smoke indicating a bad caliper. I have purchased "good" rotors opposed to the $10 dollar specials.
I need a "brake" from this problem. Any advice would be appreciated.  

Answer
There are two things that cause brake rotors to warp and cause pulsation, heat and a rotor that is at or below the wear limit, make sure that the rear brakes are adjusted correctly so that they can help stop the truck instead of the front brakes doing most of the braking, in some cases there may be a problem with the adjustment of the brake proportioning valve located at the rear but this is rare, is this truck used to tow a trailer/boat etc. because this will have an adverse effect on brake wear so will carrying a lot of weight in the bed of the truck. I would recommend installing new rotors from the toyota parts department along with the pads specified for this model along with the shim kits and the anti rattle hardware and  make sure the rear brakes are working correctly and there are no hydraulic leaks on the rear brakes or axle seal leaks which would compromise the effectivness of the rear brakes.