This thread described all the very same issues I am experiencing on my Freelander 1 td4 2006. But this has happened (apparently) different reasons given the info I have to date.
In short the car started to have a massive loss of power, but there was no clicking or knocking sound from the engine. Basically the car had no power when accelerating (so it didn't respond as expected), engine often stuttered on start, at time didn't start or took forever as if it wasn't receiving enough fuel (but checking the fuel line, filters and pumps was all working in order), a few time the engine turned off by itself as if fuel didn't get to the engine.
A tech who works on injection system and turbines advised me to change both the Common Rail Fuel Pressure sensor and the harness that connects said sensor to the ECU.
I was able to find the sensor at a local car part store but not the harness so I changed that first... the car worked even better than before, but that lasted just about 3 weeks... until now where I have the same issue described by the original poster of this thread.
What I suspect though is that there might be an issue with the harness that needs to be changed (as the tech told me) so that if any wire or contact on that harness is oxidized, corroded or damaged in any way (hence leading to the malfunction) replacing such harness should make the issue go away. This suspicion is backed also by the fact that when I brought it to my buddy who is a mechanic and who told me that the noise was being caused by injectors not operating correctly, I asked him to re-seat the connector plugged into the fuel pressure sensor at the end of the common rail "flute" and after he did that the problem went away... albeit for a short period of time and came back later in the day (probably due to vibrations causing the electrical connection failing again after it had been "fixed" after the re-seating of the connector.
I'm currently awaiting to receive the new harness I was able to find online (finally in stock where I got other parts for the freelander 1) and will post an update once I'll have it replaced (and hopefully that solve the current issues )
Thanks for the continued sharing of all your experiences and learnings on this forum!
Cheers!