1980 2.3 non-turbo charging

I have a non-turbo 80 that has a 2 wire connection to the alternator. Parts store says I should have a 3rd wire. I had 79-80 2.3's when I was younger and don't remember any more than a 2 wire hook-up. Alternator tests as good, but won't start or run w/o a jump or boost. It will also die at idle after 10 to 15 minutes... any suggestions?

thanks

Ah ha, yes it does. I had the alternator checked, it was ok. When I bought the car the guy I bought it from said he had recently replaced the regulator. I'll try that next.

Thanks