Looking back I put in Rotella-T 15w40 last change with a Bosch filter. Don't have the instrument cluster in right now or gauges so now way to verify, but seems to run fine.
Today I went and put a nice bead of RTV silicone sealant around the outer part of the booster grommet and also a ring around the vac line barb. Let it set nice and it seems thorough.
Took my Mity-Vac and connected to the line that was going to the HVAC. This line is tapped after the vacuum pump and before the check valve.
As soon as I start the car, the vac gauge rose to 28ish in. vacuum, which is good. No matter what conditions, while the car was running it stayed at a constant reading. After turning the car off, it still stayed at 28. Now somewhere I read that a working booster should drop vacuum when the pedal is depressed - but I'm not sure if that is correct, and I'm not sure if that is only true if measured after the check valve. Regardless, no change on mine. I get one solid assisted pump after the car is off.
Now if I hit the brakes hard while driving (like panic stop hard) I definitely get a full power assisted screech to a halt kind of stop. But if I'm giving it a constant medium braking effort like I would to stop normally I get some vacuum assist to wherever I hold the pedal constant, and then seem to run out. For example, if I were slowing down gradually and then had to panic stop, it is hard as a rock to depress it that second level.
Also when slowing gradually and coming to a halt when I give it a lot of pedal pressure I get this sort of vibratory/knocking feeling and noise. Not sure where it is coming from, but almost sounds like the motor shuddering. Does not seem to vary based on speed, only on braking pressure (and very hard, end of the pedal like). Don't know if maybe I've got some warping or binding at the drums, or something more sinister.
I took some video of it driving and stopping with the gauge visible. You can't really read it, but you can see that it doesn't move. The noise I'm describing is barely audible at around 0:15-0:18. Don't mind the squeaking, its just the clutch pedal.
http://www.youtube.com/watch?v=jcALI2KUFUIAt this point I feel like the vacuum pump and grommet are fine, and that it is probably a small split/leak in the booster diaphram. The only options I can seem to find on this model booster is a reman from Cardone via Auto Zone or a used booster. My normal FLAPS guys don't carry anything.