Here's an update on this annoying issue.

I took off and cleaned the EGR and verified that all the vacuum lines were routed correctly. My idle is still fubared - even worse with the colder temperatures.

Here's a re-cap of what's been done...

TPS adjusted and working correctly
Fresh coolant - burped properly
New Thermostat
Vacuum lines routed correctly
Coolant Temp sensor replaced
Throttle body thoroughly cleaned
Throttle body swapped with another one (to test the idle air control valve)
Dashpot cleaned and NOT sticking
Throttle cable lubed and NOT sticking
Timing set at 5 degrees
No check engine codes
Idle screw is IN the entire way

And like before; if I'm crawling or idling for a long period of time (15 minutes or so) my idle will gradually drop to where it's supposed to be - I even have to adjust my idle screw out a few turns.

Any other thoughts?
Triple check the vacuum lines?
Is there an Air Temp sensor on or near the AFM?