The 7.3 adjusts its timing and fuel parameters based off oil temperature. So yes, when the oil is cold, idle will increase and the EBPV will close. I would think that if the computer reads higher than 180 degrees, it thinks the truck is at full operating temperature and gives the engine full timing. (This is what I was told from Jody at DP Tuner).
I drove my truck to work today, about 55 miles, mostly highway. My AutoMeter oil temp gauge starts at 100, and after idling for 20 minutes, it still was below that. After about 5 minutes of driving it started to read above 100. Even after 20 to 30 minutes driving at 80 mph, turning over 2000 rpm, the oil temp only got to about 150 to 165 depending on traffic. The ambient temperature was about 20 deg. F this morning. My point being, that the truck never fully warmed up and wouldnt give the truck full timing advance.
My guess is, since the computer is getting false readings, it is not calculating your engine parameters correctly, and that is causing the lope and lack of high idle and EBV. From what I have been told the 7.3 does EVERYTHING based off oil temp and it is very important. Hopefully you get it figured out soon.
Good luck
Just an afterthought... if these sensors work on resistance, and I imagine they do, the sensor might be working correctly, but somewhere in the wiring there could be an issue. You said the pigtails were showing bare wires, maybe that is the case further down the line. I know chasing an issue like that is an absolute nightmare, but it sounds like the temperature moves up and down as it should, it's just starting 150 degrees too high for some reason. You might need to get a wiring schematic and check resistance from the sensor pigtail to the main harness connector pin.
