Disco 4 (LR4) Misfire at 2000rpm after changing inlet manifold

We have a 2012 LR Discovery 4 3.0 SDV HSE, with 75K miles, we've owned it since 18 months old & 24k miles. The car has been brilliant since owning it, just one gearbox sensor (which packed up on the day LR issued a recall on it) and one mass air flow 6 months ago.

However... a few weeks ago, we had the dreaded cracked inlet manifold fault.. got it replaced in the local garage but since they did this it's had a misfire at 2000rpm, which puts it into limp mode.. revs ok while in neutral. Local garage couldn't find the fault, so we took it to a LR specialist, who have now been right through it and can't find the fault either, checked the turbo's etc.. nothing..

Has anyone else had this fault, or any ideas on what the fault could be?

Thanks in advance for any help!

Believe there’s 2 inlet manifolds,
It’s quite common for the other one to fail shortly after first one,
Could it be that.?

Thanks for replying johnlad, apparantly this has been checked and ruled out, and the current (very bad) misfire is a totally different sympton to when the inlet manifold went originally..just went into limp mode and fault wiould reset itself after switching ignition off.