Overheat at Idle and in Traffic

Thought I might get answered better over here then in the 3rd gen forum.

It's hot out, my truck at idle or in heavy traffic begins to heat up and will reach about 215-220 pretty rapidly. But when I move it cools right now.

It has a 180 degree thermostat.

I'm not low on coolant or loosing it.
New Fan Clutch
New Water Pump
Few month old Thermostat

Could my radiator be clogged? or something related to my thermostat or should I fear something with a head?

Btw. I have the 5.9

Does the tstat open? pull it and stick it in some boiling water and see if it opens.

Or pull the cap when cold and see if you see any coolant flow when it warms up.

yeah, check the easiest and cheapest thing first and see what happens...but the way you're sayin it's actin maybe it's the water pump goin out?

clogged radiator!!

Ugh, ended up pulling off the cap today and finding the radiator half empty. The overflow tank was still half full. Unsure as to why. Replaced the cap and took a look under the truck to find it coming out the bellhousing again. Thought I fixed it last year. Guess not. Going to drop the trans and see if its the Freeze plug behind there again or the heads.

Hopefully not the heads, as I have no power loss or compression loss.

To be losing at that rate, and not having it show up in oil or on the block, I'm betting that freeze plug, especially if you've had trouble with it before.