Sam, I apologize for any delays been a busy week for me and with all the snow/ice i haven't logged in to the site much.
Is this a petrol navarra QR engine?
if so there are a couple of things that can cause them to go into limp mode, really depends on whats happening? are you revs limited? or what?
Thank you, ***** ***** the case there are a few things that come to mind, but since turning the engine off temporarily rectified the problem. You need to start by replacing the fuel filter and bleed the air out afterwards.
When the filter gets clogged lots of times shutting the engine off allows allows alot of the contaminents to settle in the filter long enough for a restart and operation. Only to cause it to return later when driving.
So start with the fuel filter, if the problem continues we need to explore the other possibilities like the EGR, wastegate, and MAF operation.