P0087 fuel rail pressure low limp under high loads

[Mark Rinker]

Im having the same problem on a 06. I put 8 new gm injectors in and still having the same problem. It only does it at wot and when its warm. Pump at idle you can ramp it up to 24000 psi and hold it all day. when it warms up it will command 26000 and drop to 12000

This supports my theory that its about HOT fuel, as much or more than return rates. That should have been solved with new sprays. How many miles on the truck when it first occurred?