High Fuel Rail Pressure

I recently rebuilt a Duramax LB7 and installed it in the truck. It has the common rails and a S&S diesel 10 mm stroker pump with 60% over S&S Diesel injectors. I have not tuned this truck....Yet...., but I noticed that my fuel rail pressure is 23,000 psi at idle. It doesn't seem to matter at what RPM, it stays at 23,000 psi. I rev up the engine and then it starts sputtering and cutting out. I used the same Engine wiring harness as before. The old engine was working just fine prior to swap. I swapped out the fuel pressure meter on the back of the fuel pump and it did not fix the problem ( Thought it my be defective) . The only other thing I can think of is the wiring Or maybe the ECM is keeping at such elevated levels. Is this something that can be corrected once I tuned the truck? I've been watching the videos and they don't seem to address my particular problem ( or am I missing something). I was wondering if somebody could chime in and help., Maybe make some suggestions or guildance once i get to tuning.

Overall, I got the the engine is running. It idles fine but when I rev it up, It stars spuddering. The fuel pressure stays at 23,000 psi all the time.

Appreciate the help

Bear in mind I'm not familiar with that engine, or modified diesel for that matter (been mostly stock heavy equipment).

I did find this, though, and it may be a good starting point as it seems to have quite a thorough diagnosis proceedure - https://www.dieselplace.com/threads/2002-lb7-high-fuel-rail-pressure-at-idle-help.938018/

Might be an idea to first check for wiring or connector damage, oh and fuses, because it's not unknown for them to be damaged when working on engines.