2003 GMC envoy xl

[mecj7304]

I have a 2003 GMC envoy xl 4wd v8. The other day while driving it seemed to lose power while going up hills and seem to be running hard. It started to backfire a few times after shutting the vehicle off going to restart it it would no longer start. Now it's reading a code p1518. The battery is fully charged the vehicle turns over but never fires. I replaced the fuel filter thinking maybe it was not getting gas any ideas would be much appreciated ready to pull my hair out

[dsr611]

Possible causes...

• Dead or weak battery
• Faulty Throttle Actuator Control (TAC) module
• Throttle Actuator Control (TAC) module harness is open or shorted
• Throttle Actuator Control (TAC) module circuit poor electrical connection
• Check Throttle Actuator Control (TAC) module connector for water

If battery is good like you say, then looks like you need to concentrate on the throttle actuator control