So, I jumped on I-25 South bound headed out to Rox's place to make a delivery and about 10min into the drive on the freeway at around 70-75 mph it started acting like it was running out of gas, quick look at the gauge and the aux tank was on empty, no biggie since the main was full, switched it over and NOTHING changed, still acted like it was starving. I was able to limp it off the freeway and into a gas station. Popped the hood and looked for obvious signs of problems, nothing, it would idle rough but it wouldn't sustain high rpms without gurgling. Dropped the hood and limped home at about 30mph, coughing with no power to grab the truck so I could make the delivery.
Today I was able to pull it in the garage and
around, swapped out the fuel filter since it acted like it was starving, no change. So i checked all the previous tune-up items and everything was good except the no.1 plug pictured below. The tip is loaded, metal by the looks of it when I took a file to it and the cylinder was wet with unused fuel.I always start my trouble shooting to the last thing that changed, so that is why I started checking the tune-up items. What do you guys think is the cause?

