ok, I went to start my car and nothing happened. I mean NOTHING. No clicks/anything. All the electrical is dead. Radio/windows/lights/etc. If I go out and rattle the battery a little the electrical stuff will go back on. BUT if I try to start it as soon as I hit it to start it dies again. So I rigged a screw driver to the key so it would stay in the start position and rattled the battery. FINALLY it started. So I'm driving along and all of the sudden it stalls. And it's the same thing over again. Luckily I was right down the street and when I finally got it started and just went straight home. So, what can be the problem?!?!? TIA