My gas gauge and engine temperature gauge stopped working

Hello, I feel like these are not related concerns. The fuel gauge will receive information from the fuel sending unit in the gas tank, mounted with the fuel pump. If the sending unit has failed or there is a wiring concern, the gauge will not register properly. The best testing that can be done here is utilizing a diagnostic tool able to monitor and actively command components such as gauges so that you can imitate the sending unit function and verify the gauge works when commanded. Then, reading the level as stated from the sending unit to the control module is also helpful. The temperature gauge is probably reading accurately, especially if you are having a hard time getting heat. Focus on engine cooling system operation, such as with the thermostat - is it maybe staying open or opening too early, or staying open too often? Here again, coolant temperature is something that can be monitored from a good diagnostic tool.

It sounds like your fuel pump level sensor has failed, it is a common issue with this car. The fix is to replace the fuel pump assembly. As for the heat, your thermostat could have failed. If there are check engine lights on the dash, borrow a scan tool from the auto parts store and run it to get the codes. The codes will tell you what parts are failing.