So, I went over a year unable to fill my front tank at all, and the rear would take about 15 minutes and burp out all over me and the truck. I noticed if I stuck a chunk of hose in the filler, I could get fuel in the tank. Air has to come out for fuel to go in. That is what the tube within a tube filler neck does. Someone cut the flexible fill line flush with the metal neck on both my tanks. That mod makes no sense to me because it puts the vent right next to incoming fill. Path of least resistance is right back out the vent. Stop cutting the internal fill spout when using stock vents. Distance between the two gives a better chance for air to go out the vent.
Instead, I wanted to mimic the hose in the spout vent that worked for me previously. I saw the air vent in the neck can be enlarged and let air out of the tank easier. 1/4" drill bit and a dremel made it a quick job.
Vent enlarged. There is enough metal there to go even a little larger than this.
Original vent.
Then I flushed all the junk out of the whole filler neck. You can pull each filler with the bed on. For the front tank, I needed to remove two bolts and raise the bed slightly to get the neck back in. The rear will push in fine, the front was fighting me a little. This made a huge improvement. I can now fill both tanks with standard or high flow pumps on the first click, wash my windows,etc and it will click off without overflowing. Seems to fill at a fine speed and I don't have to baby sit it. If I trickle it in after the burp I might get another 1/2 gallon in, which isn't a big deal to me.

This was pretty quick to do and took no new parts, except the unaltered filler necks from my parts truck.