Weird Idle Anomaly?

Don't rule out the possibility of getting some bad gas. Did you by chance fill it up just prior to the issues surfacing? Any change in where you get fuel?

 

I filled it about 48 hours before this started happening and probably drove about 80-90 miles between the fill-up and when this started happening. I've always used Speedway/Giant gas and almost always fill up from the same station due to its location.

 

the manual says that 91 octane was used in factory testing for average mpg

 

While I know you can justify the $ of delivering pizzas vs. vehicle wear and tear, these truck do not run well with a cold engine. You're, most of the time, barely warming up your engine and that's leaving a lot of mess behind. You at least need to get some longer drives mixed in on the highway. And your battery will suffer most likely with all those short trips because it takes juice to spark at start, then over all those quick trips it's likely not getting enough power from the alternator to top if off when you're doing 7 cold starts in a night then driving a couple of miles. Cold engine, weakening battery, and these trucks run rich at start-up to warm the cats as I understand it. So lots of things that would lead me to believe any 3rd gen is one of the worst delivery vehicles you could own. Perfect use case for a cheaper prius or hybrid of some sort....

I'm no mechanic and half of what I said may be complete BS but I sure well know my truck runs rough and feels underpowered until things warm up, after which it is smooth with plenty of power....