I have had similar problems this is my first time posting on the forum due to having got to the pulling hair out stage. Bought this model about a year ago, first drive out coil light comes on then engine light goes into limp mode as we found out latter. Injectors were sent off to Ipswich for testing came back as OK they were refitted. Worked for a while until the wife was driving on the A14 when happens again. Take the car to EMG in Bury St Edmunds. They do the diagnostic thing, a guy comes out says, yeah it's the injectors mate that will be £1200 please, I say yeah bye. Do a bit of research. Take the injectors out myself and send the to a place in Brum. The clean and complete refurb for £500. I replace and the car is sweet, runs like a dream until I take it for a spin and floor it at which point it does exactly the same thing. So It's not the injectors is it EMG £1200 ha. We use the car for a while on the instruction if you don't floor it it wont happen which works for a quite a while. Last week same thing as before happens except when come to start it it wont start. This was a period of very heavy wet conditions. Green flag man can't solve it but gets it started with spraying into the manifold.
I start an investigation with my local garage man who is also perplexed. Take the fuel filter out, the fuel that comes out looks like Kerosene same viscosity as my heating oil and deep amber in colour. We drain the tank and re-fit the fuel filter find that the glow plugs are all faulty and covered in oil and replace all of them. Now we can start the car but it is not happy lots of clonking and misfiring after running for about ten minutes it’s starts to calm down. Whilst I appreciate the bad fuel will have contaminated the injectors again, it obviously isn’t the whole story. Extra information, there is black oil deposit in the turbo hoses and we are losing some oil now which we weren’t before. Also the engine had a Dragon chip box attached which I have since removed. Any thoughts would be much appreciated. Oh the old glow plugs were black.