Excesive fuel consumption/jumpy idle

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Ok, will check coolant temperature sensor. Seems to be a pretty common problem.

If I'm not mistaking it looks like this, right?:

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So, a friend of mine has got a 2.0 just like mine for spares

Already replaced the ECT sensor with the one he had, it didn't influence the engine at all. Still burning fuel like a warship. What else should I replace now that I can get the stuff I need for free?

Was thinking about the fuel pressure regulator

Any other ideas? Don't be shy, I can pull everything out of that thing (except for the MAF, that's missing)

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Ok, got the PCV valve from the donor car, also got the fuel pressure regulator...nothing changed .
Well, at least it manages about 7L/100km at 50MPH constant driving.

I started it up today, just for a ride around the neighbourhood. Kept it under 2000rpm...the MFA said 67.1L/100KM...I'm desperate
That's just screwed up...I'm starting to get sick of this car...believe me

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Found something interesting...
A wire that was leading from the ignition coil to the ECU harness. Now it's not there anymore, somebody cut it, but you can still see where it used to be. Can't really tell why. Maybe the ECU is the fault. Got a replacement one, but can't start the car, the immobiliser keeps stepping in. I guess I should also get the immobiliser. Where is it located on the car?
How can I get it off the car?