1993 Mercury Villager Positive battery cable with connector

I believe there was a loose connection between the connector on the positive battery cable and the cable. Would that cause the following symptoms:
Battery light on
Emergency Brake light and ABS light on intermittantly
rpms waver between 400 and 900 then die when put into drive
After tightening the connection it seemed better, then when turning on the headlights, the rpms dropped and wavered again.

If it isn't the connection, what else might it be? Alternator?

Please help, van is stranded on the side of the street.

Adam