My car will start when jumped but once i take off it wont get gas and cuts off.

The *alternator* is NOT working - that's what keeps the battery properly charged and provides the case constant voltage necessary to keep the engine running.. The battery only provides the starter with power while 'cranking' the engine.. When the battery becomes discharged as the result of no alternator output - the engine will not operate without jumper cables - when jumper cables are removed - engine WILL stall. Recommend *hands-on* inspection / evaluation by qualified personnel ..