Rough Idle ?
Just to clear things up this is on a 01 7.3 W/ 190,000 miles.
Recently I had a 203 degree t-stat installed w/ the dieselsite housing. This was done along with a full coolant flush & oil change. Coolant installed is the delo elc. Oil was changed to rotella 5W-40 full synthetic.
Before this was done the coolant was never changed, only added to. I ran royal purple 15W-40 and was satisfied. Just not satisfied with the price of the oil.
My first thoughts was the lighter weight oil. But from what I was told that should help smooth out the idle & give better fuel mileage. I rarely ever tow with the truck so I figured this oil would be perfect.
Now I'm wondering if the 203 degree t-stat is causing this.