HI I have a 1994 cadillac sedan deville with the 4.9. over the past few months my outside temp reading has been geting more and more off. I was just wondering if this has anythig to do with why I have no heat....well it comes out slightly warm but not enough to make it not freezing in the car. The outside temp gauge read 72 degrees f this monring and it was 20 outside. I know that I need to flush out my cooling system but I'm not sure if it will help this heat problem or not. Any ideas or information would be greatly appreciated. Thank You

Sounds like the OAT sensor has a problem. You might check the connections to it.
Are both hoses to the heater core hot? The core could be clogged a bit. You can reverse flush it with a garden hose.
FWIW
YMMV

Try this first:

http://www.automotiveforums.com/vbulletin/showthread.php?t=894740

Please check the dates on the thread, 3 yrs old!