Fuel pressure

I doubt you are going to find a regulator for this engine that will supply you the needed pressure.

However, if your vehicle is not running correctly on 40 PSI then you more than likely have a restriction in the fuel system.

Let's start with checking the pressure to find out what it currently is because even though you have new parts on the vehicle we don't know what the current pressure is.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

I attached the info below from the manual that will help with testing the pressure.

Once we know if it is low, we will need to check the filter to find out if it is restricted.

Please run through this info and let us know what you find. Thanks