Loosing brake fluid? Check the hose going from the booster to the intake manifold for oil inside it.
It's time to tear down the master cylinder and inspect it for bad seals and deterioration.
http://www.cygnusx1.net/Supra/Librar...Section=BR&P=9
http://www.cygnusx1.net/Supra/Librar...spx?F=4702&P=1
You're going to need to clean out the booster as well once you repair/replace the master cylinder:
http://www.cygnusx1.net/Supra/Librar...ection=BR&P=20
http://www.cygnusx1.net/Supra/Librar...spx?F=4703&P=1
Make sure the check valve to the booster isn't sticking due to the contaminants in the vacuum line:
http://www.cygnusx1.net/Supra/Librar...spx?F=4703&P=2 (Make sure you put the check valve back on in the same orientation it was in originally!)
Fix the exhaust leak.