[rbarton]

Thanks for the help guys. I checked the vac booster per Ronin's procedure and it seems OK. Is there a good test for the master cylinder other than just trying a new one? The master cylinder and booster were just replaced, but I know they were cheapo rebuilds from the corner auto parts store.

One thing I just figured out after a drive today: the falling pedal problem occurs only when I apply the brakes lightly for the first couple of inches of pedal travel. If I give the pedal a good firm stab upon initial application the pedal stays firm.

Thanks again for the help. I've learned more from this site in the last 3 months than I would have believed possible. I need to get this POS fixed so I can get back to the 911.