I have a 2000 ML 320 with 102k miles with the following codes, PO300, 301, 302, 303, PO130 and PO 135. The plugs were replaced with factory plugs at 60k and the wires and O2 sensors are original. Should I just replace the one sensor, plugs and wires or both front sensors due to mileage. Also since it all is Bank 1 related is there anything else that is suspect such as the cat on that side. It doesn't seem to have a lot of pep and the mpg is down to about 14 in town.