Engine starts badly, runs rough, runs good

Fuel pressure shows 55 PSI. The fuel pressure regulator and the fuel filter are both combined w/the in-tank fuel pump. I have a filter on order and will replace it.

FWIW, the car belongs to our daughter, she just bought it a few months ago, so don't know how long the plugs have been in there. I had pulled the plugs and looked at them, they are NGK iridium plugs and looked good so I re-installed them, gap at spec of.040"
The engine has 3 spark plugs w/wires on them, the other 3 have coils on them.
Still waiting for the new fuel filter. Nobody stocks them locally.

I received the new fuel filter and replaced it, not a simple job like an external filter, but it's done.
Due to time constraints and the weather I haven't had a chance to test it yet.
I will definitely update as things progress.
Respectfully, Ken

Update,
After mulling things over I came to the conclusion that the problem must be with the ECM. I pulled the ECM and sent it to ECMdepot in Texas for repair. After a couple of weeks (Christmas, New Years) they called me and said the ECM is unrepairable, the processor is bad. I asked about getting a used ECM and having it programmed for this vehicle and was told that is not an option as they were unprogrammable.
They suggested I contact Land Rover about a replacement.
They are going to send the ECM back to me.
In the meantime I plan to do a bit more research about the ECM.

Any suggestions?

I have heard that one cannot just insert a used ECM and go, they must be programmed w/the VIN and odometer reading to work.
Do you know if this is true or just an "urban myth"?
When I replaced the ECM in my '05 Dakota the supplier wanted that info before they would send a repaired unit (exchange).
Methinks I'll do a google search and see what I can find.

Thanks, Ken

Update: In late January I sent the ECM to Bluehawk Electronics in England, they said they would either repair it or get a used replacement, program it and send it back. They were terrible to communicate with. I tried phoning them, two different numbers, no connection. I tried contacting the local police to see if they were a legitimate business or not, no reply. They finally said they sent it back to me, no explanation. Apparently it got lost in the mail as it took four months before I received the ECM back (in Royal Mail packaging). They finally told me that they could not find a suitable replacement. I got tired of trying to get this issue resolved and spending money on it so the vehicle has been sold for a parts car.
Thanks for your support, Ken