Engine starts badly, runs rough, runs good

This sounds like a fuel pressure - pump issue. Here is a guide to give you an idea of what to do to check the fuel pressure.

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

You might need an adapter to install by the filter or fuel rail.

Pressure should be 45 to 55 pounds.

If you don't have a gauge you can rent one at an auto parts store for free.

Please let us know what happens so it will help others.

Cheers, Ken

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.

Have you installed new spark plug lately? Here is a guide that will show you what you are in for when doing the job. This can cause the problem are are describing as well.

https://www.2carpros.com/articles/how-to-change-spark-plugs

Please let us know what happens.

Cheers, Ken

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.

You can't tell if the plugs are worn on the iridium plugs, you just have to replace them. Mileage only.

I would start there with a clean slate and do wires as well (OEM only). Here are some diagrams to help you. (Below)

https://youtu.be/c9_NVXiwvYg

Set gap of each new spark plug to 1.00 mm .
Fit spark plugs and tighten to 25 Nm (18 ft. lbs.) .
LH bank only: Connect ht leads.
RH bank only: Fit plug top coils to spark plugs.
RH bank only: Fit bolts securing plug top coils to RH camshaft cover and tighten to 9 Nm (6.5 ft. lbs.) .
RH bank only: Connect multiplugs to plug top coils and secure with locking clips.
Fit engine acoustic cover.
Connect battery earth lead.

Please let us know what happens

Cheers, Ken

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

Thanks Ken! yep some fuel filters can be a bear.

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?

Not programmable? First time I have heard that one but you never know. I would try getting a used one and plugging it in. This is interesting please let me know what happens

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

Please let us know what you find. We are interested to see what it is.

Cheers, 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

Sorry to hear that but every car has its life span. Use 2CarPros anytime, we are here to help. Please tell a friend.

Cheers, Ken