Do all DSL internet connections have an intermittent connection?

My DSL has a connection issues during the day, especially during the summer. It is out around 20-30% of the time. I have decided to switch to another ISP and was wondering if this would be an issue with other DSL services, or was simply an issue with some aspect of my current setup (I use earthlink and an old modem, either of which may be part of the problem).