Low fuel pressure to the fuel rail

Couple things. When you say there is not much pressure at the rail but there is at the pump, how do you know that? Did you check the pressure at the fuel rail?

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

If you did what was the PSI?

If you have low pressure at the rail, but good pressure at the pump, then you have a restriction in the line which is most likely the filter. I would suggest changing that and go from there if the pressure is good at the pump and low at the rail.