Thanks guys,

"5.9 right? Being a 98? I would suspect possible fan clutch,"
Yes 5.9 (lol) I was think fan clutch as well. over 300,000 miles and never replaced.

Poorboy, I have checked all toughs things Thats is what leading me to believe that the thermostat may have gone bad.

Rhinodart, How is the heater, good hot heat?
Good point, I will check it out.

I didn't get a chance to pull the thermostat yesterday, will do so today. It just seems strange to me that it is worse during the cold mornings then the warmer afternoons.