Network Troubleshooting

I have been having touble chronically with DNS not resolving. First thing I did was ping -t the two gateways for Covad and for PacBell and noticed that they were pinging eradically and the time=xxxms would go from 16ms to 1200+ms and then it would rto. If I unplug my outside line it restores in a few seconds. I then put 1 machine on the “outside” and pinged and did so from within my network. It was slightly better from the Covad router but not much. 2 questions:
what can be used to reset the time on a ping or icmp packet, and at what point should I go to Covad support?