Hello. First let me say that I am far more familiar with 65/66 cars than I am with 84 models.But, 14.4 is high. That is straight output from the alternator.You probably have a regulator problem.I believe that your alternator is internally regulated, so that would call for replacing the alternator.The car starts and runs fine for a few minutes and then has trouble would also be accounted for by excessive voltage to the coil. It is getting hot and breaking down on you.The not shutting off thing is probably the ignition switch. Is this a car that you have bought recently or have you had it for a while? You might want to have somebody run the codes on the car and see what the EEC says is wrong with it.The car will tell you where it hurts if you ask it right.Hope that helps.