Right, I know the meeting I did today wasn't the durango series, but I raced in the same place with the same radio. I was running a different car (F1) with a different receiver, different speedo (with power cap), different motor, different sensor cable, different servo and different battery. Still having the same problem. I re-bound the 2.4, tried different sensor cables and nothing can get rid of it.
I'm going to go again with the same gear in my buggy to the next durango round next week, but this time I'm taking a different radio set. Hopefully this will stop it and prove that its my 2.4 module. Can't think of anything else it could be now.