I have a 1971 Opel GT, with an automatic transmission, that will not stop. Lately, if I am coming to a stop, as the car slows to about 10 MPH the engine starts to increase in RPM and the brakes will not work. It feels as though I can push the brake pedal further, but they start to release and the car will not stop, or she slowly accelerates. If I shift the transmission into neutral the engine revs but the brakes work. If I take my foot of the brakes before shifting into neutral then brake, the engine does not rev and the car stops normally.
Also, lately, the car has been hesitating when I try to start from a full stop. I have to gently pump the gas pedal to get her to go more smoothly. She also has stalled several times when starting form a full stop. Not sure if this is related to the problem of not stopping?
Sounds like a vacuum leak somewhere. Most likely between the engine and transmission