Just did the vac test. 13-15in (flutter with each engine stroke). No noticeable difference between when the booster is connected or not (manifold plugged when disconnected). Pressing the brake cause a very very slight decrease in vac (maybe 1/2 in), that instantly returns.

I'm running Akebono pads.

I idle right around 750 RPMs when the truck is warm. More when it's cold.

 

I hate to suggest it, but if the booster is OK, it usually indicates an ABS issue (which ought to be setting a code). Typically the high pressure accumulator. As a Disco II doesn't have that, it leads me to suspect the ABS modulator.

I'm (fortunately for me) not very familiar with ABS modulator issues on DIIs, so hopefully someone else can pick this thread up with suggestions or other possibilities as to what could be wrong.

Edit: have you had some else drive it to make sure it's not just you? Not accusing....just to be sure you aren't expecting 911 SC brakes on a Disco

 

I am considering replacing all 4 rotors and pads on my 1999 Discovery I. Any recommendations for a source of parts?