This phase II trial is studying alvocidib and oxaliplatin to see how well they work when given with or without fluorouracil and leucovorin calcium in treating patients with relapsed or refractory germ cell tumors. Drugs used in chemotherapy, such as alvocidib, oxaliplatin, fluorouracil, and leucovorin calcium, work in different ways to stop the growth of tumor cells, either by killing the cells or by stopping them from dividing. Giving alvocidib together with oxaliplatin with or without fluorouracil and leucovorin calcium may kill more tumor cells.