We had the exact same issue that you are having in May 23 which I posted about on this forum. We initially had a new ECU fitted at Adams Morey but after a short drive it still was not giving me full power but the EML wasn’t coming on.
I ended up taking the van back to the dealer and they test drove it for about 40 minutes, the mechanic said he couldn’t really feel the van performing poorly and he had driven a lot worse.
I asked him if he could repeat the diesel run off test again ( tested a few weeks earlier and all injectors were within acceptable levels) just to check the injectors again. Thirty minutes later he returned to inform me all 4 injectors were now outside acceptable levels and recommended they all need changing.
Anyway, in total it cost us about £3000 for new injectors and a new ECU ( programmed with the very latest software) and we have now about 13,000 miles since the repair.
We continue to use the fuel additive on every fill up and I also now try and use posh diesel every few months.
I also now store the motorhome nose up to avoid the deluge of rain flowing continuously onto the screen and bonnet especially over the winter months.
For reference our van is a 2018 Ducato 2.3 150 bhp euro 6 NON ADBLU, at the time when it failed it had covered about 33,000 and it is serviced every year at a commercial dealer. The van was exactly 5 years old at the time.
