dweller,

Maybe the problem isn't the hydraulic system at all. I can't get at my spare set of pedals because I'm having an open house but there's a little spring device on the pedal assembly that can adjust the pedal tension. If it's too slack the detent falls out of position and the pedal drops to the floor.

Check this out. When everyone leaves, I'll find the pedal assembly and have a better idea but I remember it happening to me and I put more spring tension on it and never had the problem again.

Yours may have been compromised when you put the new master cylinder in.

Ben
www.reproduce100s.com