The O2 is 99% needing to be replaced.

 

So... 2 years later the problem is finally solved.

I have replaced almost everything that has to do with fuel and intake air. The MAF, spark plugs, catalytic converters, fuel pressure regulator, fuel vapor valve, injectors and even some of the mufflers.

Countless tests done regarding vacuum leaks, fuel pressure and timing.

Yesterday after a long day of work I was having a beer with a mate and this topic of conversation came up. We both thought it was strange that there was no intake manifold pressure sensor on the Jaguar, but could still calculate a value to adjust the timing. Then we went to look at which possible sensors this value could be based on. Eventually we came to the idea that the throttle position sensor was not positioned correctly.

Sure enough, we turned it about half a millimeter and .. problem solved.

 

The interdependency issue strikes again.