Well I have almost the same problem but my mids & tweets on the right side are at half volume wile the lft side is loud (yes my deck is set to the middle of all lft rght speaker) I sent my Fosgate in and the said it was fine the 2 thing I have lft to check are the speakers them selves along with the crossovers.
Then the deck might be the channels or the wires are out.
I just havent gotten to it cause its a lot of tight wiring in my car since my Zapco compulinks are all in the way!
Hope that give you some where to stick your nose in too!
