OK so I finally got around to testing the car fully with VAGCOM. Here are the results:
Chassis Type: 1H - VW G/J/V Mk3
Scan: 01,02,03,08,15,25,56
-------------------------------------------------------------------------------
Address 01: Engine
Controller: 037 906 025 R
Component: SIMOS 4S 2104
Coding: 00000
Shop #: WSC 99999
1 Fault Found:
00513 - Engine Speed Sensor (G28)
16-10 - Signal Outside Specifications - Intermittent
Readiness: N/A
-------------------------------------------------------------------------------
Address 03: ABS Brakes
Controller: 3A0 907 379
Component: ABS ITTAE 20 GI V00
Coding: 03604
Shop #: WSC 00000
2 Faults Found:
00287 - ABS Wheel Speed Sensor: Rear Right (G44)
35-00 - -
00287 - ABS Wheel Speed Sensor: Rear Right (G44)
16-10 - Signal Outside Specifications - Intermittent
-------------------------------------------------------------------------------
Skipping Address 15-Airbags
-------------------------------------------------------------------------------
Address 25: Immobilizer
Controller: 1H0 953 257 B
Component: IMMO VWZ3Z0T1071555 V00
Coding: 09600
Shop #: WSC 00675
No fault code found.
End
Randomly I tried the scan again after a few times and it does not pick the 00513 - Engine Speed Sensor (G28) fault up?

I am also confused as the speedo is working fine, its just the engine revs drop, the ECU relay clicks rapidly and lose power. Sometimes it starts straight after, others not for a while.
So I assume it's the crank sensor? I have had a poke about and I think this is the sensor? and the wiring seems damaged. Would this cause the problems I outlined at the start of the post?



Interestingly a fault I was getting about 8 months ago from VAGCOM about the Lambda sensor now does not show:

Should I still replace the Lambda also?
Thanks
