I need help figuring out what to do with my furnace. It is a Lennox gas fired fuirnace model G1203-110-3 and is over 20 yrs old, not one of the new energy efficient furnaces, and the pilot keeps going out at night resulting in some cold evenings. If it is the Thermo Couple, can it be replace easily enough and how? If it's not the thermocouple, what else may be wrong?
Thanks

I would definitely start by replacing thermocouple. Easy job. It will be located right next to the pilot. It has a copper tube leading to the gas valve. Unhook it at both ends, take it to your local hardware store, get a new one, reinstall, and presto, (hopefully) no more problems. If this doesn't cure the problem, let me know and we will take it one step at a time.