Annoying temp gauge

[duckdog27]

The temp gauge on my 94xlt fluctuates from N to M in minute intervals. When I turn on the heat the gauge goes all the way to L. What could be the problem. I have replaced the coolant temperature sensor. Do I just need to flush the coolant system?

 

[Electrohacker]

try the ..uhhh... thingy...uhh.the...thermostat... that'swhat cpould be doing this

 

[duckdog27]

I replaced the thermostat a week ago and that did not seem to help.

 

[Electrohacker]

I would try a flush then... but uhh other than that I have no idea... make sure it's a deep flush...