When running the car (3.4L V6, Auto) there is a noticeable intake backfire coming from the air intake tube. I have checked the spark (looks yellowish) and checked the input voltage at the ignition control module. It is two volts lower than battery output voltage (i.e. battery is outputting 12.5 volts, and the voltage at the module is 10.5 volts). So, I checked voltage at the fuse (under hood) and it is at 10.5 volts too. Why would there be such a large drop? Is there a wiring diagram for power distribution for the fusible links, so I can trace out the wires and check all hidden graounds?