I'm going to have to agree with everyone here and say that you need a better iron. It's a one time investment, and it will help your soldering out LOADS! Trust me, it will!
I hate to suggest this. NO, I REALLY hate to suggest this, but you can get the Hakko knock off soldering station from hobby king for about $20. I have the Hakko 939 (I think) and it's the shiznit! But, It has the $100 price tag to prove it too. If you get a hotter soldering iron, you will be able to do these joints without melting the plastic on those deans connectors. Make sure when you are soldering deans, you plug the other side in.