All patients receive ifosfamide IV by continuous infusion for 2 days, etoposide IV over 2 hours daily on days 1 and 2, and filgrastim (G-CSF) subcutaneously (SC) daily on days 4-13. Courses are repeated every 21 days. Patients who have complete or partial remission after a minimum of 4 courses of chemotherapy receive maintenance therapy consisting of interleukin-12 SC twice weekly beginning on day 28 of the final chemotherapy course and continuing for 6 months or until disease progression. All patients also receive combination antiretroviral therapy during study.