After seeing the low temp at the end of the 20 mile run, I came to the conclusion the t-stat was stuck open or missing. I received my new t-stat and expansion tank cap today (along with my tires and oil pressure sender), and hope to do a coolant flush with new hoses and t-stat this weekend.
The miss at cold idle was erratic, not steady so I ruled out a mechanical miss. Since getting the timing dialed in this afternoon the cold miss seems to be taken care of, I'll wait until I get the engine temp up to par and see how the hot idle is looking.
I guess I was looking for verification of my methodology.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.