Electric Static Issue

[Wolfman213]

06 Base w/ M&T. I installed my new headunit, a Kenwood KDC HD942U, and I used the PAC OEM-2 Universal Interface, instead of the Schoshe model simply because the what Crutchfield had and had a 60% discount with it.My issue is in the rear speakers only, I and getting an electric sounding static, not white noise. Sorta sound like when you are plugging or unplugging a guitar with everything on, that's sorta like the static I'm getting. I soldered all of the connections together and used some heat shrink and electrical tape when need. (This was my first REAL soldering job. I didn't do too bad of a job.) The manuel for the PAC OEM-2 stated that the RCA outs were wired at the same location as the regular wires. Since they have are not connected to anything and they did not come with rubber caps, is it possible that they are touching something metal, going back into the PAC OEM-2, then traveling through the connected wires? Is there something else that I should look for? Also, there was an extra plug in the back of the factory unit that had about 6 or 8 wires that I didn't know what to do with so it's just "there" for now.Any help would be appreciate so I have a clue what to look for tonight. Thanks in advance!!!