Ok here is the deal. I have an '01 4x4 with 64k on it. about 5 k I just replaced all 4 rotors (brembo cross drilled front/brembo oem in back) and put hawk pads all around. I did this because I had horrible stopping power when I had to "jump" on the brakes to avoid, say a deer, in the road.

While stopping did seem to improve I still don't think that I have the stopping power I should. So 2k ago I did a brake fuild change from the original fluid to the castrol low moisture absorbing dot 4 fluid. I really don't feel much of an improvment.

Now I have realzed this. When I do normal braking usually the petal travels a certain distance (say 2 inches for this discussion) before I start to feel the brakes grabbing. Now if I have to do a sudden stop I can put the petal on the floor and the truck starts to slow down but the longer I keep the petal there the quicker the trucks stops to the point where the ABS kicks in. Perhaps to better explain it, the braking power is not linear. The braking power gets more powerful the longer the pedal is on the floor.

Now after this the brakes which I would feel start to grab when the petal is depressed 2 inches, now start to grab at 1 inch and the braking system is more powerful and break power feels more linear. However, over time (say 30 sec-3 min..i have not timed it) this "better breaking" goes away and fades back to normal.

At first I thought it was the brakes/pads heating up but I have tried this in various conditions and the results are always the same.

I am lost as to where to go now. Should I replace the master cylinder or the break lines or what?

After driving my wife's escape ('03 w/20k) for the first time in a while I realized how bad my brakes feel now and want to fix it.