Aparrently they all do that, and it seems a little worse on mine than it was.
I have found out details of a home made plug which has been used with success - basically a 10k B3950 NTC thermistor in series with the air intake temp sensor.
The bits have arrived, easy to make into a loom that can be plugged in - so dont have to cut the existing loom to fit.
Plan is to put it together this afternoon and give it a go.
Bits cost me about £10 which is much better that the £120 odd quid that seems to be the retail price.
I'll report back later......