Let's kill or thrill the bad brake booster idea once and for all...
Borrow or buy a vacuum gauge & connect it to the vacuum tree where the booster connects. Start the engine and let it warm up. At idle speed, you should see 16"-19" of vacuum. Increase the engine speed to 1000 RPM and the vacuum will increase slightly, maybe to 18"-21" of vacuum. If you dont have at least 16" of vacuum or more, then you have vacuum problems. The booster needs a minimum of 12"-14" of vacuum or more to work properly.
To test the booster, start the car and let it idle for 2 minutes, then increase the engine speed up to 1000 RPM and hold it for 30 seconds. This gets your vacuum up to it's highest point.
Shut off the engine and press the brake pedal. You should feel some give in the pedal. Repeat the process 3 or 4 times. The pedal should get harder each time. If it does not, the booster is probably bad.