coolant leaks onto the pass. floor board think it's my heater core

Your heater core is leaking, no doubt. Check these out for an idea of what to pay and where to go. https://repairpal.com/estimator/volvo/s70 https://repairpal.com/volvo-repair-in-dallas-texas

buy one off the web and follow this: http://www.volvo-forums.com/t22870-1998-volvo-v70-heater-core-replacement-w-pics.htm