Hello and thank you for trusting us with your question. I'm DJ.
I can tell you up front that this isn't going to be easy to diagnose. Nothing like, 'replace this relay' or 'these two wires are crossed.'
The first thing I would do is look closely at the wiring to the oxygen sensors under the truck. Whenever there's an EFI fuse blowing, about 80% of the time that's where the problem is. With wiring harness comes out of the clip and rubs against the exhaust. This melts through the insulation to the oxygen sensor heaters.
Next I would look at any aftermarket equipment and where it's wired in to see if there's a problem.
At this point you'll need to make a tool. Take an old headlight bulb and attach two wires to it so that if you apply power to the two wires, the headlight bulb bright beam will illuminate.
Then take these two wires and plug them into the fuse box in place of the EFI fuse. When the circuit is shorted, the headlight bulb will be fully bright. When it's not shorted, it will be dim.
This way you can jiggle wires, plug things in and out and not have to worry about burning anything up or continuing to blow fuses.
I know this is a bit odd, so if I need to explain it a different way, please let me know. It's the best method I've ever found for finding and fixing short circuits.
So check the wiring to the 02 sensors, check for any problems with aftermarket stuff. If you don't find anything, make the tool and we'll continue from there.