Overheated main fuse block? Specifically fuel pump relay?

[drtccc]

Has anyone experienced their 2016 5.3 start to stutter and act like it was running out of fuel or the fuel pump not keeping up during very hot weather? I was hauling 1,800# in the bed while it was 110 degrees, moderate traffic, both fans were working correctly on high, the engine starting stuttering as I pulled into a parking spot and died. It restarted fine so I shut it down again. No idiot lights and all temps showing normal. I popped the hood to let it cool for a while. Started it again after about 45 min, truck went about 300 yds, stuttered again, no throttle, then died. this repeated about 6 times, sometimes making it less than 100 yds. I initially thought the fuel pump was going out, so I smacked the tank like old times, no better. It finally dawned on me that the truck started after cooling down for a while. I took the lid off the main fuse block, all fuel pump fuses checked out. The relay was switched for another and both started clicking after cooling for a while, so it overheated. I left the fuse block cover off, left the hood popped and drove a mile to a relatives house with no problems. After letting it cool for 45 min with the hood up, the truck ran fine the rest of the drive with the hood popped and fuse block cover off, over several mountain passes and 100+ heat. Maybe the ECM overheated too but didn't pop any codes? I have one pusher fan to help with cooling. I am wondering if anyone has cut out a few of the molded slots in the plastic cowling that seals under the hood? It seems the hot air has to be forced out and down the firewall and over the trans, instead of being able to escape up and out like hot air wants to. It seems like everything above fender level just heat soaks. Ideas?