AGG conversion wiring diagrams? Lambda on Elvis.

[Resynth]

I just bought a T25 with an AGG engine installed with what I am told is an "Elvis loom".
Really like the van but it's not running super great and kw1281test is giving me Lambda sensor error codes.
The lambda sensor connector has been snipped and juggled about and I'm not sure how it's supposed to be.

On the loom there is a four pin connector and looks like it was originally:

1.  Red/white wire to a fuse (Heater 12v?)
   
2.  Brown wire to ECU pin 19
   
3.  Yellow wire to ECU pin 16
   
4.  White wire to ECU pin 4
   

That's as best I can tell but I can't find a pinout for the AGG ECU anywhere.  Does anyone know what these pins are and what they are supposed to be connected to on the lambda sensor?
If I restore the wires to those pins then can I just plug in a MK3 GTI lambda sensor and everything should be correct?
Do wiring diagrams exist for these Elvis looms so next time I'm confused about something I know where to look?
Do pinouts exist for the ECUs?

Cheers :^)