Rear Brake problems - won't stop squeeking....Ideas?

Ok all here is the deal.

I had a new set of rotors / pads put on about 6-7 months ago along with my suspension kit. Since then I have had a squeek in my back brakes. The squeek is there when I am NOT on the brakes. Just the littest pull on the ebrake or a little pressure on the pedal they shut up.

I have tried 3 different brake pads, different brands too. Even turned the new rotors once already to make sure they are flat.

So what could this be?
-Could my cobra brakes up front be causing me problems? Pressure valve?
-Bad rotors (they are brembos)?
-Brakes are just screwed up?

The car is at the shop now since they are putting on new tires and are going to look at my brakes again.

The shop is thinking it is a heat disipation problem so they suggested I may need new drilled or slotted rotors? They do squeek more when warm, when cold in the AM they are usually quiet.

Ideas?

~K

The first set (Hawk HPS) gave me the worst problems. I was actually at the beach 3 hours from home and they started making a horrible noise. Firestone said the spring on the pads that are supposed to hold them in place were bad.

So they put on new ones. Those started squeeking a few days later.

My local firestone replaced those pads, and they are noisy too. I can't see 3 different pads all not being seated correctly. Unless there is a problem with my caliper or the brackets or something.

~K

Well I talked to the shop and they said it is a problem with my proprtion valve. They are saying my Cobra brakes up front are messing up the value and the rear's are getting too much pressure.

This confuses me since my cobra's have been on for almost two years. Cna the valve go bad?

~K

san~man,

The problem is my rear brakes, and I have the stock GT's in the rear. Only my fronts are Cobra's.

~K

Plus I have tried 3 different pads, no motorcraft's yet though.