You need a consumer lawyer in WA which you can find at www.naca.net. They will be able to advise you of the applicable statute of limiations which may or may not have renewed with your payments in 2008.
You may contact Luke Wallace at Humphreys Wallace Humphreys P.C. at 918-747-5300 or Luke@HWH-LAW.com. For more information see www.HWH-LAW.com. The response above is general legal and business analysis. It is not "legal advice" but analysis, and different lawyers may analyze this matter differently, especially if there are additional facts not reflected in the question. I am not your attorney until retained by a written retainer agreement signed by both of us. I am only licensed in Oklahoma. See also avvo.com terms and conditions incorporated as if they were reprinted here.
Making a voluntary payment does renew the applicable statute of limitations for debt in Washington.
We would need to know the nature of this debt to determine the right statute of limitations. Most consumer debts are based on contract, and have a 6 year statute of limitations.
Best of luck,