In a message Stephen writes:

>I have a servo/vaccuum assist 
>master cylinder after filling and bleeding the system I decided to take 
>it out.  Well when I use the brake it lugs down the engine and will 
>quickly kill it.

It sounds like either the vacuum diaphragm in the servo has got decent sized
hole in it, causing a massive vacuum leak or the one-way check valve (located
on the line near the manifold) has failed.  Replace the check valve (about
$10 new) and see if that solves it.  If not, maybe it's time to replace the
vacuum line or the booster/servo unit.

Jim / BusBoys@aol.com