Well, the PO135 is saying the driver's side upstream O2 sensor is bad--so just replace it. And the PO102 is saying the MAF has low frequency. You can take a voltmeter and check to see if you have between 4 and 6 volts. If not, the wiring is bad somewhere--at the connector, in the wire loom, etc. Try looking at the connector to see if the pins are properly seated.