Audio Systems: sound system, cadillac sedan deville, amplifer

Question
I have a 1995 Cadillac Sedan Deville and me and one of my friends installed an aftermarket system 2 12s a 7" in-dash dvd player and a 1200 wt amp, the car was workin good only about 80,000 miles, the ac went out and every since then I've been havin problems I fixed the ac and now my car seems to die real quick and I have to recharge the battery a lot, when me and my friend instaled the system we found out the car already has a 10speaker factory system with factory amp we couldn't figure out how to wire the aftermarket system to the factory and couldn't find anyone that would mess with this specific car for that reason. So we bought speaker wire and rewired each speaker in the car to the back of my deck but when we did we didn't do anything to the factory wires except tape the ends up. Is that my problem?  

Answer
there is a factory amplifer in the trunk
left side behind the carpet  unplug that amp because it is on full time that is the reason that the battery dies if you don't drive the vehicle

sometimes amplifier is behind the rear seat and seat needs to be remove