1999 Vauxhall Tigra engine over revving

Last month I had an issue with this car cutting out and losing power. I found a loom with 3 cables in that ran down the left hand side of the engine (above the cam belt) had been trapped under the cover that bolts on top of the engine. Two of those cables had rubbed bare and were going to the Coolant Temp Sensor. I duely tapped up those cables and the car started playing fine although the ecu light would come on after a short time which I assume points to a temperature related issue. I was going to change the Coolant Temp Sensor this weekend but....... now the engine is running high at up to 4000rpm when in nuetral and the ECU light is still on. The third cable the the loom I original found has a spade connector going to the top of another sensor about 2" to the rear of the Coolant Temp Sensor - this connector whilst looking solid, actually "spins" as if designed to do so. Can anyone enlighten me if it should? Im close to cracking this Im sure