Combination Chemotherapy in Treating Patients With Recurrent, Refractory, or Metastatic Solid Tumors or Lymphomas

DISEASE CHARACTERISTICS: * Diagnosis of cancer that has failed standard therapy or for which no such therapy exists, including, but not limited to: * Unresectable primary or recurrent solid tumors (e.g., colon, pancreatic, lung, esophageal, or cholangiocarcinoma) * Metastatic disease * Lymphoma with no prior high-dose chemotherapy requiring autologous or allogeneic stem cell rescue * No leukemias * No CNS metastases or primary CNS malignancies * No failure on prior gemcitabine therapy PATIENT CHARACTERISTICS: Age: * 18 and over Performance status: * ECOG 0-2 Life expectancy: * Not specified Hematopoietic: * Absolute granulocyte count at least 2,000/mm\^3 * Platelet count at least 100,000/mm\^3 Hepatic: * Bilirubin no greater than 2.0 mg/dL * Transaminases less than 6 times upper limit of normal Renal: * Creatinine no greater than 2.0 mg/dL Other: * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * No other serious concurrent medical illness that would preclude study * No active infections requiring IV antibiotics * HIV negative PRIOR CONCURRENT THERAPY: Biologic therapy: * See Disease Characteristics * More than 4 weeks since prior immunotherapy and recovered Chemotherapy: * See Disease Characteristics * More than 4 weeks since prior chemotherapy (at least 6 weeks for mitomycin or nitrosoureas) and recovered * At least 3 months since prior suramin * At least 5 weeks since prior eniluracil (8 wee…