Code P0087, misfires, lacks power and the high pressure drops

Okay, do you suggest I do a fuel pressure test to compare it to the output of the sensor before I just change parts? Also, the O2 sensor stuck is of concern, I changed that sensor last week.

Here are the other codes present:
P0087 Fuel rail pressure too low
P00C6 Fuel rail pressure too low - engine cranking
P0456 EVAP leak - small leak
P2196 O2 sensor signal stuck rich B1S1

Pulled live data on B1S1 - it is stuck at 1.02v doesn't move on graph under throttle movement.

So, I was planning to replace the high pressure injection pump, but because it didn’t arrive today, I thought I would try your suggestion of changing the low pressure sensor. I replaced it to no avail. So I removed the fuel injection high pressure fuel pump and found a failed cam follower and high wear on the pump as well. Some minor marring of the cam, so I suspect it will go out in the future as well. I’m not sure if this is what you had in mind for next steps, but this is where I am. Any suggestions as to why the B1S1 sensor is stuck rich?

Okay. Mystery solved. Low pressure sensor changed, no result. Snap on software says pump failure is the most probable cause. They were right. Upon removal of the high pressure pump, I discovered that the cam follower was worn through, and the pump actuator was riding on the cam. No Bueno. Owner didn’t agree with my opinion that the flattened lobe on the cam and the missing cam follower parts were ruining the engine and that the only responsible repair was a rebuild. Showed him the known issue documentation from Ford, and so I have to guess the bad news was just hard to accept. Anyway, installed new cam follower with assembly lube, new high pressure pump, and it runs well and all issues resolved. The time bomb went out with a clear and fair warning to the owner that the car was no longer reliable. We can only hope he doesn’t trade it in with this issue disguised by my repair.