Just trying to be proactive my little sister drives a 2004 xc90 2.5l, recently her power steering pressure hose ruptured spraying power steering fluid everywhere.she tried to mickey mouse the problem with duct tape made it worse. I replaced the line. Now her engine is knocking. Vacuum leak appeared on her diagnostic check. Along with 3 other codes for misfiring cylinders...clogged injectors? Would a fuel additive work? Shoud I switch out the spark plug & coil packs? Any feedback would be greatly appreciated