Happened to me recently so I hit up my local Mitsu dealer and replaced all the coolant hoses Both radiator hoses ,both heater hoses, the two hoses off the throttle body, both of the hoses for the oil cooler and the two hoses off the thermostat housing cost a little over $100.00 . The hoses took a week to arrive though. Your best bet is to replace all the hoses for reliability and peace of mind.