catalytic converter is possible but you would have efficiency fault codes so i thing that still good, to rest fuel trim is best to use Volvo scan tool to reset but you can try this if it don't work that you have to try scan tool if after scan tool fault codes comes back that replace exhaust manifold gaskets .to rest remove both sides battery cables from battery tape both ends together for 30 min this will discharge all ecu in car reconnect both leads to battery and test drive it.
also check if you loosing fuel pressure at rest.with fuel gauge.
Technician
10 Years Volvo Master Cerified Mechanic ,ASE Advanced Certified.I'm in Chicago area
adaptive values get reset best thru volvo scan tool but it works with disconetting battery how i told you.