overheating problem..Help

[joegr]

I have an 04 Lincoln ls 3.9l. I have been having this issue with the car not over heating but the fan runs high when idling for a few seconds. When I start to drive it lowers down. I have definitely noticed this when driving in 5th gear. I have change the thermostat and housing, Degas bottle a few times. I have had the system bleed which helped but only for a period of time. Any idea why the fan keeps doing this?

First off, it is overheating, just not enough to move the temperature gauge.
You need to replace all the plastic cooling system parts and correctly fill and bleed it. Also, all the parts need to be Motorcraft, not Dorman or similar.
Details on the parts here: GenII LS8 Cooling System Overhaul