2005 Ranger 3.0 STX My check engine light comes on if I let it idle with the A/C on. PO303 and PO316 I replaced plug wires, plugs, coil pack, #3 injector, fuel filter and pump unit and checked injector wiring with noid lights, I also bought the kit to clean MAF sensor and throttle body. I really thought the pump replacement had fixed it because it starts easier but I drove it 30 miles after replacing the fuel pump and filter and stopped and let it idle with the A/C on and the check engine light came on. It runs great on the highway but it has a somewhat rough idle. What do I replace now? O2 sensors??