Help me AEU86, you're my only hope

[Nakilad]

So, i was finally able to get back to the car today for a few hours. I'll start by answering the last two comments:

@the Doctor, I dropped the exhaust off at the end of the exhaust manifold and started the engine. Made no difference that I could tell, apart from being quite a bit louder!

@rsr-k No difference, check the videos though underneath though,

@totta Crolla, The O2 sensor is just plugged into a Prosport Gauge. Single wire narrow band sensor, mounted in the exhaust manifold as seen in the later models. It is therefor unheated. I have tried 2 distributors, and moved the timing from between 10 and 15 degrees (static) with no noticeable effect.

@jondee86, I have a pressure gauge mounted to the fuel rail at the moment. Fuel pressure is perfect at idle (2.2 bar (32 psi) from memory) and jumps to close to 3 (43 psi) when blipping the throttle from idle.

So, I was unable to really check the voltages from the MAP sensor as jondee86 was mentioning, ran a bit out if time and don't have a mightvac handy to verify the vacuum to voltage.

I did however find something interesting/ strange. I have been measuring the output of the O2 sensor with a digital multi-meter with the +ve attached to the wire of the O2 sensor and the -ve attached to the battery -ve. This showed 0.14 volts and the gauge registered as lean. Then for whatever reason I moved the -ve of the multi-meter to the +ve terminal of the battery. This gave a reading of -14 volts (as you would expect), but additionally, the gauge now show the mixture in the optimal range! Something is still not right however as in this condition, blipping the throttle causes the gauge to register lean rather than rich.

To help with this, I made a few short videos of the various conditons and uploaded them to my youtube channel (Playlist here). Maybe something in there will ring a bell?

If I can get the car running normally at idle I would be happy to go for a quick squirt up the road, but as it's not had a TÜV for almost a year now I don't want to do that too much!

As always, I appreciate all the ideas, thanks for trying to help me out here.