I'm having sort of the same thing happening I believe.

Just did DPF delete and left everything unplugged all the EGR stuff under the hood.

Recently installed banks intake horn and werli fab cold air intake and now it is acting like it doesn't want to build past 8psi boost in 6th gear going uphill and sometimes seems like its surging.

RaceME Ultra on 2018 6.7 Cummins 68RFE