I have the issue where I'm unable to fill my tank up continuously. Sometimes I can pump 0.5-0.75 gallon before the handle trips, sometimes I can only pump 0.02 gallons at a time... (that's when I rage out).

This weekend I removed the EVAP canister assembly, broke everything down and blew it all out. There seemed to be no blockage, and I could blow into the line back to the tank. When I put it all back together and went to the BP up the road, it still persisted (and it was one of those 0.02USG occurrences...).

Any other ideas? It's an 04 XLT 4.0 4WD, and yes, I've tried holding the handle at every conceivable angle, from every degree and depth, and squeezing the lever at any and all possibilities.

 

EVAP system is a vent of sorts but not used as a vent for filling the gas tank, hose is too small for that and solenoid is closed when key is off in any case.
The point of an EVAP system is to prevent gas fumes from escaping the gas tank while driving and while sitting.

Air vent for all fuel tanks is next to or inside the filler hose.
In a 2004 Ranger it is part of the filler tube and next to it.
It will be a smaller metal tube welded on to the larger metal filler tube.

Picture here: 2004-2005 Ford Ranger Fuel Filler Neck

If you remove the gas cap you can see its round opening about 3-4" down inside the tube.
It has a separate rubber hose attachment on the gas tank end.

When you insert the gas pump nozzle it should go in past the vent opening, as gas flows down the larger tube air can escape out the smaller tube.
If the smaller vent tube is pinched or blocked then air has to escape out the larger tube which causes gas to backup and that triggers the nozzles "overflow" sensor.

Check that smaller tube

 

Wow, thank you! I started with the EVAP/charcoal canister because that seemed to be the most commonly suggested course of action.

What's the best way to check that smaller tube? Do I need to pull that whole unit out (would that require dropping the tank), or just pull the rubber line off and check that?

 

I would first look at the hole inside the filler neck, make sure nothing is blocking it.
Then get underneath, look and feel what you can of that tube.

But yes, pulling off the bed, which can be easier, or dropping the tank would be next.

But dropping the tank can also cause the issue you are having because you have to hook up the filler and vent hoses then lift the tank into place which can cause vent hose to twist or bend, that prevents air flow out of the tank.

Google: Pulling the bed off ford ranger