does this 2004 envoy have a fuel filter? how often should it be changed?

The fuel filter is in the fuel tank and is not meant to be changed unless the tank is out or the pump is being changed. Foolish in my view, I liked having a filter you could change.

It does have a external fuel filter. It is located under the drivers side door inside the frame. You should pull the fuel pump relay and run the truck until it stalls so that you don't spill more gas than necessary. The filter is about $12 and you can buy a tool to remove the filter from the hoses though I have been able to pinch the clips with my fingers to remove them. I try to change mine every 30,000 or so.