Thanks for getting back to me. The plugs for 3 and 4 came back out and went back in fine so I don't think they are cross threaded, all the plugs went in no problem. I could stick the old plugs back in a see if it runs ok.
I have VCDS and although the check light is not on I get this for the engine (checked this morning):
1 Fault Found:
000256 - Mass Air Flow Sensor (G70)
P0100 - 004 - Supply Voltage
Freeze Frame:
Fault Status: 01100100
Fault Priority: 2
Fault Frequency: 1
Reset counter: 255
Mileage: 71730 km
Time Indication: 0
Freeze Frame:
RPM: 0 /min
Load: 0.0 %
Speed: 0.0 km/h
Temperature: 12.0°C
Temperature: 10.0°C
Absolute Pres.: 970.0 mbar
Voltage: 11.938 V
Readiness: 0000 0000
Any one know how to test the MAF harness?