The 7.3L engine should put out 17-19 PSI boost in optimal conditions, or at least 15 with higher mileage. I'd be a little concerned about the ICP at 2500 PSI under WOT. The pump on this system can create 5000 PSI and should start the engine at 500-700 PSI.
If you notice your truck has lower power after getting to operating temperature, or has a hard time starting when hot only, I'd look to a weak high pressure oil pump.
It's hard to work through the forum... do you have any more details about the power loss condition?