I have a '92 Mazda MX3 5-speed V6 that will not start. It appears that the battery is not charging. I replaced the battery but the car continues to require a jump to start. The car consistently stalls when in neutral and I let off the gas. The alternator appears to be working as I have had it tested and started the car and disconnected the positive battery terminal; the car did not stall. What is a possible cause for the battery not charging and for the stalling.