Hello from noobie
I have a 166 2.0TS from 2000 (done 133K) and it has developed two, maybe related problems.
First it cuts out while driving along, the speedo goes to zero, but the revvo stays up. Switching ignition off and on cures the problem. Tonight it happened when I was driving along at a steady 60-70mph on a straight road.
Secondly, every so often, well maybe even every journey, the speedo and the revvo will go berzerk and point shakily downwards until the end of the journey.
My wife thought it was related to the engine trying to steady at idling after coming down, so I cleaned the throttle body tonight. Hopefully this will help, but I doubt if it cures the problems.