Quite an unlucky day

[Mathmatic]

Good day everybody!
I own a 2009 Pontiac G3 wave which has been troubles free until today. It currently have 33700kms. First I was on the highway and I saw the speedo moving up and down. I was going around 3200-3300rpm in fifth gear so basicly 118-120km/h but speedo was showing sometime 0 some time 60 then back to 120 down to 80km/h and did that for over 2 hours what could be the cause? Then there was a taxi in front of me who lost it's top light which I've been hitting hard. I then pull over on the sholder to look for damage everything seem to be fine no leakage etc. I then heard a strange uneven noise like an unsteady idle I went inside the car to look at the RPM and it was steady around 800rpm which is perfectly normal. I drove back home and on my way I saw the temperature gauge went down completely. During my drive back home I felt that the clutch was not reacting normally but a similar way that I expect when I just start driving at -15C. I wonder if it's been acting this way because the engine was cold? Finally when I made it to home I went outside look and feel the engine temperature it's seem to be cold and the fan was working continuously. I let the engine run at idle for a couple of minutes and I saw the engine temperature rising. What could be the cause of all of this? Thanks!

[xintersecty]

It could be a bad ground wire day. Can you put a thermometer on a water line and make sure it's steady. Compare that to the gauges and see if they are going up or down. It could be the wiring harness to the instrument cluster is loose or a bad component in the cluster.