Towing I have tried to always run 93. I’m sure I’ve forgotten before but I’ll be sure to try and run 93 from now on.When I did my tests with different octanes while towing I found that the engine seemed to run a little cooler the higher the octane. The PCM can advance timing more, for a longer period of time on the higher octane. I found only a slight difference between 87 and 91 that is blended with ethanol. However, if you can find NON-ethanol 91-93, then the differences are much more noticeable. The cost of pure gas however negates any savings over blended 87. In fact, it may end up costing you more because you don't gain an equal amount of MPG to make up the difference.
Now if you routinely ran 87-89 in the past, you shouldn't have to put higher octane in the tank to "regain" performance from before. So if your habits haven't changed, but the truck has, then I would still focus on fixing the truck's performance.
The PSI readings from this morning are perplexing though. I talked to our company mechanic about it and he had the same puzzled look on his face. We decided if the two sensors are the same part number maybe I should flip-flop them, and see what happens.