I have had this furnace serviced a few times its an 1980 interherm Ive had the sequnizers replaced the limit switches the fan and all new wires and it has worked fine for about three years then the other morning I woke up to a house full of smoke and my filter was on fire. I don't want this to happen again, I got it running the ac now and its working fine seems no problems, what else could it be any Ideas before I Have the service guy come out and scratch his head.

Well, lets start with the furnace is over 32 years old, they do not last forever. I'd contact an Interthern rep and get his read on your furnace issues. Sometimes they are worth fix and other times not. Intertherm Heating and Cooling Products (http://www.intertherm.net/)

I really don't have a lot of money and two kids to protect so if replacing it is my best option then that is what I have to do, I just don't understand I have replaced almost everything on it could it be in the elements?

At this point call an Intertherm rep just for his assessment of what's wrong, what it would cost to fix and what to replace. Get him to give you all the numbers so you will be better informed. Then call 3 other HVAC companies and get their bids to just to see if they can beat Intertherm.

What's the deal here? I gave you a website to find a Intertherm rep, not a how to fix it link. Didn't you read what I actually said? From what you wrote you aren't't fixing thing yourself, you need a hvac guy to give you an onsite assessment. Why the negative rating?