Make sure & check the hoses b4 you go to all the trouble (probably fairly easy & CHEAP) of pulling the core to whether it really is the core or hoses. I'm not sure if it's easy or not on a '98. Seem to remember a lot of changes to access from 80's & early 90's setups. On our 94's, the core itself should be R&R in 1/2 hour. You will have to go through burping system again to get that air pocket out.