1994 Se problems

On start up in the morning my Gp will peg the temp gage once it warms up after a few minutes with the temp lite lit the gage will start to drop back down to a more normal operating temp until this happens you have no heat.Sometimes the low coolant sensor lights up also even tho the coolant level is fine.
I've replaced the thermostat and flushed the radiator and heater core but the problem persists.
Anyone with an opinion please email me at rolldabones01754@yahoo.com
TIA i really love this car and don't want to get rid of it 194,000 miles to date.

Welcome to AF!! You have air in the system that is not allowing the coolant to properly circulate. The low coolant light is due to the air so you need to work on removing it otherwise you will cause damage to the engine.