OBJECTIVES: I. Evaluate the 1 and 2 year event free survival of patients with poor prognosis, relapsed or refractory intermediate or high grade B-cell non-Hodgkin's lymphoma who receive high dose carmustine and melphalan plus gemcitabine followed by rituximab (IDEC-C2B8 monoclonal antibody; anti-CD20 monoclonal antibody) plus sargramostim and consolidation chemotherapy with alternating dexamethasone/cyclophosphamide/ etoposide/cisplatin plus gemcitabine and paclitaxel/cisplatin and compare these figures to a historical control population. II. Evaluate the ability of posttransplant rituximab therapy in combination with sargramostim (GM-CSF) to control and further treat residual lymphoma remaining after high dose therapy in these patients. III. Evaluate quality of life parameters and assess the risk of secondary malignancies following this treatment regimen in these patients.