The purpose of this study is to test the combination of the chemotherapy drugs Gemcitabine, bevacizumab, and docetaxel with valproic acid to treat patients with metastatic sarcoma. Valproic acid is used by people who have seizures to prevent seizures from happening; however, its use in cancer is investigational. This study will help define the proper dosing of this valproic acid. We will assess the safety of valproic acid with the combination of the above chemotherapy drugs and check for possible side effects. Valproic acid may improve the function of the chemotherapy drugs against the cancer.