2006 f250 drops rpm over 4k

[Brmon2002]

I have 2 2006 f250's that I've been fighting 1 of them for 10months now
All fuel lines, filters and pumps have been changed or swapped. Ecm, cam sensors, now on other motor. Runs about 15 mins and drops rpm to approx 2500 I can shut off for about 45 seconds and it runs like brand new again
Thinking next step is in the throttle sensors??
Any different ideas?

[rodbolt17]

like I said
two ways to test/troubleshoot.
1 step back 15 ft and chunks wads o cash at it.
2 systematically check/test each suspected item.

starts with YDS, whats on the display when it fails?
what codes have been stored and how many hours ago?
do you have block water pressure sensors?
do you have speed sensor?
what guage package do you have.

all tests MUST be done at the failure RPM and load.

[rodbolt17]

in the time you have spent blindly swapping crap and running the risk of tearing up both motors, it could have been fixed.

like I said, two methods.