Land Rover Repair: temperature gauge fluctuating, land rover discovery, temperature gauge

Question
I have a 1997 Land Rover Discovery.  I recently replaced the thermostat with a new one.  Now the temperature gauge begins to fluctuate after I have driven on the highway and then go into stop & go traffic.  I have been told it may have an air pocket or partially blocked radiator. The temp gauge doesn't go all the way into the hot but will rise then fall abruptly back into the middle range.  Any ideas?

Thanks,
Steve

Answer
It certainly sounds like you have air trapped in the system.  If so, you can probably work it out by switching heat off and on, and driving.  You may also want to read the Land Rover overheating articles on the Robison Service blog and website.  

Good luck
John