I have a 96 f-250 psd 4x4 manual trans, and the e-brake light comes on and then dims slowly and then goes out while I am driving, and it does this repeatedly. I had a 97 same truck and it would come on and stay on, so I replaced the vacume pump and that cured it. The vacume pump on the 96 is brand new. I have tried wd-40 on the e-brake switch to no avail. Any ideas? Thanks.

It may seem obvious but it's commonly overlooked. how full is your master cylinder? If the fluid is sloshing around and tripping the low level sensor while sloshing, it could cause the red light to come off and on like you say. The most common cause of low fluid is low brakes.