Hello, I am new on this page, but I can tell you that I repaired several problems of these, and it is typical in old cars, the problem is regularly inside the distributor with the docks or counterweights I do not know how you tell you, but a way of buying it is to disconnect the emptiness of the progress of the spark and accelerate it, if you persist you will have to disassemble the distributor and buy your state, in ancient cars, in ancient cars you Western dry or fat fills with dirt, depending on the car and your model this is frequent in them.