i replaced the alternator on it cause when i took the positive off it would shut off, it still does it with the new one, so i tested the old one and it was good so what could be the problem

And why are we unhooking it? Do not advise to unhook positive cable to test if an alternator is bad. Could potentially short out some of your electronics. Old school cars this was not a problem but with newer ones you could end up in a mess. Is battery not staying charged? Is gauges jumping around? If so test battery and check battery connections. Also check the negative battery connections on the frame and motor. All connections must be clean and tight for the alternator, battery and all electronics to work properly.

I did replace battery with new one cause it was bad and it still messing up so I'll check all my connections to the ground on chassis and starter, thanks again and I won't disconnect the positive again, you were a great help.