1964 T-bird stalls when I shift from park to drive or reverse

[thunderbird solutions]

Car has been sitting for about 2 years. Idles just fine in park or neutral. When I shift to drive or reverse motor stalls out. and you have to keep the brakes on hard. Jumps forward or reverse before stalling.

 

[stevetheweave1]

My guess and it is only a guess is the two things I know happen when shifted into gear is, possible vacuum leak in neutral safety switch to brake release or brake booster vacuum leak. I am more inclined to guess brake booster, does the car stumble when you just step on brake without trying to shift in gear?