11yr old federal tax debts do I still have to pay?

Yup. They don't go away by just ignoring or avoiding them..in fact they get worse as penalties and interest accrue.The idea of a statute of limitations may have relevancy, but if the debt is because you didn't file the SOL never even starts, and if you have been notified (or they even tried to notify you about it) and you ignored them, didn't answer fully, asked questions back or didn't receive the letter, the SOL stops running during that period.