1995 Mazda MX6 Erratic Temperature Gauge reading.

Engine Cooling problem
1995 Mazda MX6 4 cyl Manual 178000 miles

I've just bought a 95 MX6 recently and was told that the temp gauge and the fuel gauge will sometimes max out all the way to the right. Sometimes just the fuel gauge will do this, other times it's the temp gauge. Now both gauges are maxed out.I know I have about a half tank of fuel and the temp usually reads around half as well.

I was told by a shadetree mechanic he believes I have a bad coolant temperature sensor. I went and bought one and installed it, the problem still remains. When I installed the new one it didn't go in as easily as the old one and think I may have damaged some threads in the process. However it does not leak. I know this is a lot at once. Please help me sort this mess out. Thank you.