since i have owned my 98 disco the temp gauge has only worked one time, where is the temp sensor located, is it a one wire or two wire sending unit? is this normal on these things to give problems and would this affect a fast idleing issue? i would like to know what the temp is since it just overheated last night.

 

Did you check the coolant levels?

 

Sounds like your temp sensor is either failing or has a ground problem. As fot the fast idle problem, most likelky your stepper motor is dirty, probably cleaning it will help.
Mike