I have a 1999 ford escort zx2 that is having some electrical issues. 1st off the vehicle has troble starting up. It will crank and crank and crank, then finally it will turn over. It quivers/shutters while driving, and the headlights don't always work. It also idles very hard and sometimes dies completely when I turn on the air conditioning. I have replaced all things obvious (MAS, Plugs, Wires, Alternator, etc.) I can't find the root issue. Please help.