May be time to check into a different ISP hajo.
I was having similar problems 6 months ago. Ended up switching my DSL provider.
Went from 150 ms & scattered packet loss. Routing that went from Fargo ND, to Maryland, then KC, then Denver, then SF, back to denver, then to HTC.
Different isp, went to 40-45 ms, no packet loss, straight hops right down to HTC. Same basic provider (qwest) but different isp's, different routing, total different result.
Best is of course someone in same area with similar service though a diff company.
Get them to ping HTC for you.