I dont know alot about chips but is your super chip a custom tuned one, like specifically for your pcm?
Most off the shelf type chips come with all the tunes for every PCM and model of truck if you get a custom tuned one it will be just for your truck, which may help.
I just have a Superchips Tuner which programs my PCM. I'm not sure how "smart" the tuner is figuring out how you are equipped, but my tuner is for 97-03. I suspect it is a rather generic program applied to any of those years. I think that is part of the problem, but can't confirm.
As for boost PSI it sounds like normal, but boost doesnt equal more horse power if there is nowhere for the air to go then getting more psi wont help. If it can get all the air it needs then getting a bigger turbo would help.
I found a leaky up pipe which may be contributing to my problem. This is probably causing the lost of some exhaust pressure which causes the lost of boost and less air flow. That is now fixed but I won't know until this weekend if helps. I'm also going to modify my AIS filter system to add the second fender intake. More air....
Also your waste gate; mine likes to open a little early especially if im stuck in mud and just givinin it to her, yours may be stuck, a good upgrade is a Waste Gate controller which can be set (be careful not to over do it for your stock turbo).
I don't think the wastegate is too big of a problem, but I will find out. I also ordered a new pressure line from the solenoid to the wastegate actuator as I don't think the rubber fittings are holding pressure which is also another boost leak.
Nothing else seems to be wrong.
How big is the trailer or hill? If this is a new problem when was the last time you washed the radiator out (they can plug with dirt causing super high temps), also gearing like 4:10s dont like to go fast, a few other things contribute to but not as much.
The trailer is a 42' fifthwheel and weighs about 11,500 dry. The hills vary greatly as I live in Colorado. I expect steep hills to be an issue, but when driving highway speeds on inclines, I don't want or feel the need to back off. I expect I run the stock program, the EGTs would still be an issue, just not as quickly. The engine temp isn't a problem, its just the exhaust temps. I have 4.10 gears, but speed isn't dictating when the problem happens, it is load based at highway speeds (55-70).
Thanks for your insight. I'll post any findings.