What brand/model is the amp? It sounds like there is something wrong with one of the channels but I don't know anything about that. All I would do is be sure to check and double check the wiring connections. And just wondering - what size wire did you use?
Bad amp? Try flipping your rca's around on your amp... does the problem move or stay in the same spot... if it moves.. possibly bad RCA's/connection...
This is my new question :
Okay, so my amp has 4 slots for speakers (2 per speaker). I would like to get maybe two more subs, but how would/could i go about doing this?
You'd need to get a splitter to get power to another amp and set of subs. But that should eat up all of your trunk space.