iPhone will charge but won't connect to PC.

Hello everyone!

I have an iPhone 4 from my dad. He took it with him to work and used it everyday. Well, it seems that that caused lint and dust build-up. So I cleaned the dock connector, pins, and the space inside with some toothpicks, air, and a toothbrush. First off though, I could charge the device by a 5V wall charger, secondly, if i plugged into my PC and Mac, it wouldn't recognize it. It would boot it up if it shut down, but then nothing else would happen. So I did my cleaning method above, this enabled me to now receive the message of "malfunctioned, but recognized." This is a good sign as it's pretty obvious I've alleviated some of the dirt from the Data pins. As I look at them, they all look clean, but no matter what, it still says malfunctioned. The pins are all there with no sign of corrosion as far as I can tell. So, what could be wrong? Could dirt still be messing with my connection? How can I clean it? Alcohol?