[ImperialCrown]

By 'nothing there', you mean that the pedal is soft and low? I would start with a 4 wheel brake inspection (rear drum?). Look for loose or worn hardware.
Is the master cylinder fluid level still OK? Master cylinder issues can be intermittent. I would think that a booster issue would be more consistent.
You can downshift to 3 or L if you need engine braking downhill.

 

[Bob Lincoln]

I've had this happen before. If you didn't have any recent service or repairs, and the fluid is full and clear, it's very likely the master cylinder. Definitely get it fixed right away.

 

[98gcawd]

I do manually downshift it, but downshifting into third works for a while and then it will upshift usually at the worst time, like going into a turn. L is fine unless the speed drops below 30 mph at which it abruptly slams down into 1st with engine rpms going thru the roof, not much use for a lot of the tight turns. The '67 Dart GT I grew up with would stay in whatever gear you put it in, all day long - a low tech version of AutoStick.

Pedal feels like it will go to the floor but it's not low. The Missus complained about the brakes a few months ago at which time I replaced the front rotors and the pads all the way around. I had never experienced the problem she had with the brakes until the other day - very unsettling. :scared:
I didn't have to crack open the hydraulics and the fluid level is good. All brake components are in great shape and no corrosion at all. Recently got new tires and the owner commented on how clean everything was. I guess this vehicle has never been in the rust belt or the mountains.

So it sounds like an intermittent master cylinder problem? What brand of master cylinder should I get or request? I HATE messing with brake hydraulics. I might have to actually pay someone else to do it.

Thanks guys