I have a new battery, starter and alternator but something keeps draining the battery when I’m driving and it dies.
Battery Not Charging
Your alternator is not charging. More then likely there is an issue with one or more of the wires in the wiring harness. This is quite common on older vehicles. The wiring becomes brittle.
Use the wiring diagram provided to check it against yours. You may need to use a multi-meter to check for continuity of each wire. Check the connections and by all means check at the battery for charging. You should see over 13+ volts with engine running.