GTV6 brake diagnosis help needed

[Obadiah Fayth <fayth@domain.elided>]

Hello everyone,
	I've been having a tough time figuring out what is wrong with the
brakes on my gtv6 lately and I was hoping someone out there in digest land
might me able to help. The vehicle in question is an '83 GTV6 that I picked
up a few months ago and have been slowly rebuilding (it had been sitting
for a long time before I bought it).
	When I got it the brakes felt really bad, the pedal sank way down
before having any effect and it didn't feel like the calipers were clamping
very tightly though I could lock 'em up if I really stomped on the pedal.
The rear rotors were grooved so I replaced them. Then I replaced the pads
front and rear, replaced the three brake hoses, rebuilt the rear calipers
and bled the system, but the brakes still didn't work of feel any better.
Arg!
	So, thinking there is not that much left to replace I replaced the
master cylinder which looked like it had just started weeping around the
rear seal. I put in a good used 20mm unit off an earlier car, but the
problem still persists. I did pull the brake booster check valve from the
plenum and it is not sticking. The hose to the booster is clear and the
booster is getting vacuum. One odd thing I have noticed is that when the
car is not running the brakes feel normal (haven't tried driving it that
way though). Start the engine and the pedal sinks way down. Anyone have any
ideas?

- -Obie

Tacoma, Washington
'78 Alfetta GT
'83 GTV6

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