adrian brazda

Hello, hoping to get some help. I have a 2015 sierra denali 6.2. I'm having issues with the fuel. I hooked up a scanner and it shows desired fuel pressure to be around 2000 and the actual would drop to 400 while taking off under a load. If I ease into it it runs good. I've change the high pressure fuel pump. Is there a relieve valve or a pressure regulator that would cause this?