99 Nissan Altima GXE help

So i have a 1999 Altima GXE that i am having problems with, i am always having to jump start it and when it is started sometimes it just dies when u stop and also when you turn the air on all the way.
If you have any ideas to what is wrong please share.
Thanks

Please check the battery condition first.

check the battery

we had the old battery checked and it said good but we still had our doubts so we went and bought a new one and it starts up just fine, but now the alternator is going bad.
Thanks